Joe Mathis works as a pianist in a local restaurant. He makes $8.50 an hour.
He was able to work 39 hours last week. How much money did he make that
week?

Answers

Answer 1

Answer:331.5

Step-by-step explanation:

Answer 2

Multiplication is the process of multiplying. The amount that is made by Joe last week is $331.5.

What is multiplication?

Multiplication is the process of multiplying, therefore, adding a number to itself for the number of times stated. For example, 3 × 4 means 3 is added to itself 4 times, and vice versa for the other number.

Given that Joe Mathis works as a pianist in a local restaurant. He makes $8.50 an hour. He was able to work 39 hours last week. Therefore, the amount that is made by Joe Mathis in the last week is,

Amount made by Joe = Amount paid per hour × Number of hours

                                 = $8.50 per hour × 39 hours

                                 = $331.5

Hence, the amount that is made by Joe last week is $331.5.

Learn more about Multiplication here:

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Related Questions

What does "a' control in a graph of * f(x) = ax + bx+ c?​

Answers

Answer:

the stretch or compression of a quadratic, and if it's opening up to down.

Step-by-step explanation:

The set A = {1, 3, 5}. What is a larger set this might be a subset of?

Answers

Answer:

Step-by-step explanation:

A larger set that a particular set can be a subset of is a Universal set. A universal set is parent where all other sets are derived from.

For example, given a universal set U = {1,2,3,4,5}, a set A = {1, 3, 5} is said to be a subset of the set U because the elements of set B are contained in the Universal set U.

Also, sets like {1, 4,5} and {3,4,5} can also be regarded as the subset of U since all the elements of the sets can be found in the Universal set U. Hence the correct name of the set is a UNIVERSAL SET

So, the number of maximum subsets we can create from the given set is 8.

Subsets:

The subsets of any set consists of all possible sets including its elements and the null set. Let us understand with the help of an example.

Example: Find all the subsets of set A = {1,2,3,4}

Solution: Given, A = {1,2,3,4}

Subsets =

The subsets of any set consisting of all possible sets including its elements and the null set. Let us understand with the help of an example.

Example: Find all the subsets of set A = {1,2,3,4}

{}

{1}, {2}, {3}, {4},

{1,2}, {1,3}, {1,4}, {2,3},{2,4}, {3,4},

{1,2,3}, {2,3,4}, {1,3,4}, {1,2,4}

{1,2,3,4}

So, the formula is [tex]2^n[/tex].

The given set is,

[tex]A = \{1, 3, 5\}[/tex]

Here the number of an element is 3.

So, the maximum number of subsets we can create is,

[tex]2^n=2^3=8[/tex]

Learn more about the topic Subsets:

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1. Let the test statistics Z have a standard normal distribution when H0 is true. Find the p-value for each of the following situations:
a) H1:μ>μ0,z=1.88
b) H1:μ<μ0,z=−2.75
c) H1:μ≠μ0,z=2.88
2. Let the test statistics T have t distribution when H0 is true. Find the p-value for each of the following situations (provide an interval if the exact one cannot be found using a table):
a) H1:μ>μ0,n=16,t=3.733
b) H1:μ<μ0,df=23,t=−2.500
c) H1:μ≠μ0,n=7,t=−2.250

Answers

Answer:

1 a  [tex]p -value = 0.030054[/tex]

1b   [tex]p -value = 0.0029798[/tex]

1c  [tex]p -value = 0.0039768[/tex]  

2a  [tex]p-value = 0.00099966[/tex]

2b  [tex]p-value = 0.00999706[/tex]

2c  [tex]p-value = 0.0654412[/tex]

Step-by-step explanation:

Considering question a

  The alternative hypothesis is H1:μ>μ0

   The test statistics is  z =1.88

Generally from the z-table  the  probability of   z =1.88 for a right tailed test is

    [tex]p -value = P(Z > 1.88) = 0.030054[/tex]

Considering question b

  The alternative hypothesis is H1:μ<μ0

   The test statistics is  z=−2.75

Generally from the z-table  the  probability of   z=−2.75 for a left tailed test is

    [tex]p -value = P(Z < -2.75) = 0.0029798[/tex]

Considering question c

  The alternative hypothesis is H1:μ≠μ0

   The test statistics is  z=2.88

Generally from the z-table  the  probability of  z=2.88 for a right  tailed test is

    [tex]p -value = P(Z >2.88) = 0.0019884[/tex]    

Generally the p-value for the two-tailed test is

    [tex]p -value = 2 * P(Z >2.88) = 2 * 0.0019884[/tex]    

=> [tex]p -value = 0.0039768[/tex]  

Considering question 2a

    The alternative hypothesis is H1:μ>μ0

     The sample size is  n=16

     The  test statistic is  t =  3.733

Generally the degree of freedom is mathematically represented as

        [tex]df = n - 1[/tex]

=>     [tex]df = 16 - 1[/tex]

=>     [tex]df = 15[/tex]

Generally from the t distribution table  the probability of   t =  3.733 at a degree of freedom of  [tex]df = 15[/tex] for a right tailed test is  

       [tex]p-value = t_{3.733 , 15} = 0.00099966[/tex]

Considering question 2b

    The alternative hypothesis is H1:μ<μ0

     The degree of freedom is df=23

     The  test statistic is ,t= −2.500

Generally from the t distribution table  the probability of   t= −2.500 at a degree of freedom of  df=23 for a left  tailed test is  

       [tex]p-value = t_{-2.500 , 23} = 0.00999706[/tex]

Considering question 2c

    The alternative hypothesis is H1:μ≠μ0

     The sample size is  n= 7

     The  test statistic is ,t= −2.2500

Generally the degree of freedom is mathematically represented as

        [tex]df = n - 1[/tex]

=>     [tex]df = 7 - 1[/tex]

=>     [tex]df = 6[/tex]

Generally from the t distribution table  the probability of   t= −2.2500 at a degree of freedom of  [tex]df = 6[/tex] for a left   tailed test is  

       [tex]t_{-2.2500 , 6} = 0.03272060[/tex]

Generally the p-value  for t= −2.2500 for a two tailed test is

     [tex]p-value = 2 * 0.03272060 = 0.0654412[/tex]

Why do we study?give me reason

Answers

Answer:

Simple to help us improve our lives

Answer:

To do good in school

Step-by-step explanation:

the thing is teachers want us to study so we remember whatever is on the test for an example and that is good but not alt of people always study.

What value of a will make the following equation true?

Answers

Answer:

a=16

Step-by-step explanation:

Answer:

A=4

Step-by-step explanation:

Question Help When purchasing bulk orders of​ batteries, a toy manufacturer uses this acceptance sampling​ plan: Randomly select and test 36 batteries and determine whether each is within specifications. The entire shipment is accepted if at most 2 batteries do not meet specifications. A shipment contains 3000 ​batteries, and 3​% of them do not meet specifications. What is the probability that this whole shipment will be​ accepted? Will almost all such shipments be​ accepted, or will many be​ rejected?

Answers

Answer:

The probability is [tex]P(X  \le 2 ) = 0.9072[/tex]

The company will accept 90.72% of the shipment and will reject [tex](100 -90.72) =  9.2\%[/tex] of the shipment , so many of the shipment are rejected

Step-by-step explanation:

From the question we are told that

   The  sample size is  n =  36

   The  proportion that did not meet the requirement is  [tex]p =  0.03[/tex]

Generally the probability that the whole shipment is accepted is equivalent to the probability that there is at most 2 batteries that do not meet the requirement , this is mathematically represented as

     [tex]P(X  \le 2 ) = [ P(X =  0 ) +  P(X =  1 ) + P(X = 0)][/tex]

=>   [tex]P(X  \le 2 ) = [ [^{n}C_0 * (p)^{0} *(1-p)^{n-0} ] +  [^{n}C_1 * (p)^{1} *(1-p)^{n-1} ] +  [^{n}C_2 * (p)^{2} *(1-p)^{n-2} ]][/tex]

Here C stands for Combination (so we will be making the combination function in our  calculators )

So

=> [tex]P(X  \le 2 ) = [ [^{36}C_0 * (0.03)^{0} *(1-0.03)^{36-0} ] +  [^{36}C_1 * (0.03)^{1} *(1-0.03)^{36-1} ] +  [^{36}C_2 * (0.03)^{2} *(1-0.03)^{36-2} ]][/tex]

=> [tex]P(X  \le 2 ) = [ [1 * 1 * 0.3340  ] +  [36* 0.03 *0.3444 ] +  [630 * 0.0009 *(0.355 ]][/tex]

=>[tex]P(X  \le 2 ) = 0.9072[/tex]

The company will accept 90.72% of the shipment and will reject [tex](100 -90.72) =  9.2\%[/tex] of the shipment , so many of the shipment are rejected

 

Can someone who knows Pre Calculus help me on these questions.

Answers

Answer:

the answer should be B:12/5

The temperature at 6 a.m. was −12°F. At 11 a.m. the temperature was 0°F. Which of the following shows the temperature change from 6 a.m. to 11 am?

Answers

Answer:

+12 degrees

Step-by-step explanation:

You never showed a picture, but im pretty sure this is correct

I hope this helped, please mark Brainliest, thank you!

At a school, there are 120 athletes. The ratio of boy athletes to giri athletes is 3:5. How many of the athletes are girls?
А
75
B
45
с
24
D 5

Answers

Answer:

a

Step-by-step explanation:

because there are over half girls and half of 120 is 60 and 75 is over half

The mean and standard deviation of a random sample of n measurements are equal to and ​, respectively. a. Find a ​% confidence interval for if n. b. Find a ​% confidence interval for if n. c. Find the widths of the confidence intervals found in parts a and b. What is the effect on the width of a confidence interval of quadrupling the sample size while holding the confidence coefficient​ fixed?

Answers

Complete Question

The complete question is shown on the first uploaded image

Answer:

a

[tex]33.55 <  \mu < 35.5[/tex]

b

[tex]34.03 <  \mu < 34.969 [/tex]

c

Generally the width at  n =  49 is mathematically represented as

   [tex]w =  2 *  E[/tex]

    [tex]w =  2 *  0.952 [/tex]

     [tex]w =  1.904 [/tex]

Generally the width at  n =  196 is mathematically represented as

   [tex]w =  2 *  E[/tex]

    [tex]w =  2 *  0.4687 [/tex]

     [tex]w =  0.9374  [/tex]

d

The correct option is E

Step-by-step explanation:

From the question we are told  that

   The sample mean is  [tex]\= x  =  34.5[/tex]

    The standard deviation is  [tex]s =  3.4[/tex]

Generally given that the confidence level is 95% then the level of significance is  

       [tex]\alpha = (100 -  95)\%[/tex]

=>     [tex]\alpha = 0.05 [/tex]

Generally from the normal distribution table the critical value  of  [tex]\frac{\alpha }{2}[/tex] is  

   [tex]Z_{\frac{\alpha }{2} } =  1.96[/tex]

Considering question a

From the question  n  =  49

Generally the margin of error is mathematically represented as  

      [tex]E = Z_{\frac{\alpha }{2} } *  \frac{s }{\sqrt{n} }[/tex]

=>   [tex]E = 1.96*  \frac{ 3.4 }{\sqrt{49} }[/tex]

=>   [tex]E =  0.952 [/tex]

Generally 95% confidence interval is mathematically represented as  

      [tex]\= x -E <  p <  \=x  +E[/tex]

      [tex]34.5 -0.952 <  p < 34.5 + 0.952[/tex]

=>    [tex]33.55 <  \mu < 35.5[/tex]

Considering question b

From the question  n  =  196

Generally the margin of error is mathematically represented as  

      [tex]E = Z_{\frac{\alpha }{2} } *  \frac{s }{\sqrt{n} }[/tex]

=>   [tex]E = 1.96*  \frac{ 3.4 }{\sqrt{196} }[/tex]

=>   [tex]E =  0.4687 [/tex]

Generally 95% confidence interval is mathematically represented as  

      [tex]\= x -E <  p <  \=x  +E[/tex]

      [tex]34.5 -0.4687 <  p < 34.5 +0.4687[/tex]

=>   [tex]34.03 <  \mu < 34.969 [/tex]

Considering question c

Generally the width at  n =  49 is mathematically represented as

   [tex]w =  2 *  E[/tex]

    [tex]w =  2 *  0.952 [/tex]

     [tex]w =  1.904 [/tex]

Generally the width at  n =  196 is mathematically represented as

   [tex]w =  2 *  E[/tex]

    [tex]w =  2 *  0.4687 [/tex]

     [tex]w =  0.9374  [/tex]

Now when the sample size is quadrupled i.e from n = 49 to  n =  196  

The width of the  confidence interval  decrease by 2 from 1.904 to  0.9374  

Plot the x- and y-intercepts to graph the equation.



y=−x−5

Answers

Answer:

See the graph

Step-by-step explanation:

Graph the line using the slope and y-intercept, or two points.

Slope:  − 1

x-intercept: (-5,0)

y-intercept:  ( 0 , − 5 )

Caleb and Emily are standing 100 yards from each other. Caleb looks up at a 45° angle to see a hot air balloon. Emily looks up at a 60° angle to see the same hot air balloon. Approximately how far is the hot air balloon off the ground?

a) 44.3 yd.
b) 63.4 yd.
c) 73.2 yd.
d) 89.7 yd.

Answers

B hope the helps you

Answer:

B. 63.4 yards.

Step-by-step explanation:

(3)/(5)x = (2)/(5)x + 8

Answers

Answer: x=-19

Step-by-step explanation:

The zeroes of the function are:
A) -2 and 0
B) 0 and 4
C) -2, 0, and 4

Answers

It would be C because they are the ones that función in , I think not sure

I want to decorate my room with leaves and turkeys for Thanksgiving. The number of leaves is twenty more than twice the number of turkeys. The number of leaves is ten less than 4 times the number of turkeys. How many of each type of decoration should I use?

Answers

Answer:

50 leaves, 15 turkeys

Step-by-step explanation:

set up an equation

l = leaves

t = turkeys

l = 2t+20

l = 4t-10

2t+20=4t-10

30=2t

15=t (so that means that there would be 15 turkey decorations, but we're not            done yet)

substitute (either equation):

l = 2(15)+20

l = 30+20

l = 50 (so this means there would be 50 leaves)

hope this helps!

Manuel can walk 5 miles In one hour. At this rate, how many miles can he walk in 8 minutes? Round to the nearest tenth

Answers

Answer:0.6666664

Step-by-step explanation:

You take 5 and divide by 60. Then multiply by 8.

2/3 of a mile.

If he can walk 5 MILES a hour, lets use 5/60.

Multiply 5/60 by 8 since each minute he travels 5/60 of a MILE.

You get 0.66(repeating) OR 2/3

Tell me what quadrant this angle is in.

Answers

Answer:

Second quadrant

Step-by-step explanation:

[tex] \because \: \frac{ \pi}{2} < \theta < \pi \: bounds \: second \: quadrant \\ \\ \therefore \: \sin \theta = \frac{4}{5 } \: lies \: in \: second \: quadrant.[/tex]

NEED HELP PLEASE ANSWER

Answers

Answer:

I think its 1430 miles

Step-by-step explanation:

1430 miles he was right

Statistical significance at the 0.01 level is __________ than significance at the 0.05 level .

a. less informative
b. more difficult to achieve
c. easier to achieve
d. less costly

Answers

Answer:

d. less costly

Step-by-step explanation:

Statistical significance level is the probability of rejecting the null hypothesis. Statistical significance at the 0.05 level is the standard level for rejecting the null hypothesis.

A significance of 0.01 shows that there is strong evidence to conclude that the null hypothesis is not true. A 0.05 significance is the most used level while 0.01 is used when multiple tests are conducted or when the researcher is not so sure if the null hypothesis should be rejected. It increases the amount of evidence required to prove the null hypothesis and it also reduces the possibility of obtaining a false positive.

Please help with this easy fraction problem <3

Answers

18 + 7/9

14 + 7/8

First, rewrite each fraction in terms of a common denominator. 8 and 9 don't share a common multiple until 8 * 9 = 72, so we have

7/9 = (7/9) • (8/8) = (7 • 8)/(9 • 8) = 56/72

7/8 = (7/8) • (9/9) = (7 • 9)/(8 • 9) = 63/72

Next, write each whole number in terms of fractions with the same denominator. We have

18 • 72 = 1296  ==>  18 = 1296/72

14 • 72 = 1008  ==>  14 = 1008/72

Write each mixed number as an improper fraction:

18 + 7/9 = 1296/72 + 56/72 = (1296 + 56)/72 = 1352/72

14 + 7/8 = 1008/72 + 63/72 = (1008 + 63)/72 = 1071/72

If the backpack and book together weigh 18 + 7/9 pounds, and the backpack without the book weighs 14 + 7/8 pounds, then the book alone weighs the difference, call it b :

b = (18 + 7/9) - (14 + 7/8)

b = 1352/72 - 1071/72

b = (1352 - 1071)/72

b = 281/72

Convert this to a mixed number. 72 • 4 = 288, so 72 • 4 - 7 = 281:

b = (72 • 4 - 7)/72

b = (72 • 4)/72 - 7/72

b = 4 - 7/72

b = (3 + 1) - 7/72

b = 3 + (1 - 7/72)

b = 3 + 65/72

he pulse rates of 179 randomly selected adult males vary from a low of 43 bpm to a high of 115 bpm. Find the minimum sample size required to estimate the mean pulse rate of adult males. Assume that we want 90​% confidence that the sample mean is within 3 bpm of the population mean. Complete parts​ (a) through​ (c) belo

Answers

Answer:

97

Step-by-step explanation:

Given that:

Low = 43bpm

High = 115 bpm

Error = 3

α = 90%

To find the range estimate :

Standard destviation = (high - low) / 4

Standard deviation = (115 - 43) / 4

Standard deviation = 72/4 = 18

The sample size,(n) :

n = [(Zα/2 * sd)/E] ²

2 - tail = (Zα/2) = 1.645

[(Zα/2 * sd)/E] ² = [(1.645 * 18) / 3]² = (29.61/3)²

= 97.41

Sample size = 97

15 tens 7 ones what is the answer?

Answers

Answer:

157

Step-by-step explanation:

Answer:    15 tens and 7 ones in standard form would be 157. If you have 15 tens this means that you are adding 10, 15 times or multiplying 10 by 15, which gives you 150.

Step-by-step explanation: Hopefully this helped!

I don't believe I was shown how to complete this

Answers

Exact form: 1/5
Decimal form: 0.2

Problem 9.4 Given the system of equations -3x2 + 7x3 = 4 x1 + 2x2 - x3 = 0 5x1 -2 x2 = 3 (a) Compute the determinant. (b) Use Cramer’s rule to solve for the x’s. (c) Use Gauss elimination with partial pivoting to solve for the x’s. As part of the computation, calculate the determinant in order to verify the value computed in (a) (d) Substitute your results back into the original equations to check your solution.

Answers

- 3 x₂ + 7 x₃ = 3

x₁ + 2 x₂ - x₃ = 0

5 x₁ - 2 x₂ = 3

(a) I suppose this is asking for the determinant of the coefficient matrix.

[tex]\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}[/tex]

Using a cofactor expansion along the first row, this reduces to

[tex]0\begin{vmatrix}2&-1\\-2&0\end{vmatrix}-(-3)\begin{vmatrix}1&-1\\5&0\end{vmatrix}+7\begin{vmatrix}1&2\\5&-2\end{vmatrix}= 3(0 - (-5))+7(-2-10)=\boxed{-69}[/tex]

(b) Using Cramer's rule, we have

[tex]x_1=\dfrac{\begin{vmatrix}\mathbf 3&-3&7\\\mathbf 0&2&-1\\\mathbf 3&-2&0\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]

[tex]x_2=\dfrac{\begin{vmatrix}0&\mathbf 3&7\\1&\mathbf 0&-1\\5&\mathbf 3&0\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]

[tex]x_3=\dfrac{\begin{vmatrix}0&-3&\mathbf 3\\1&2&\mathbf 0\\5&-2&\mathbf 3\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]

That is, solving for n-th variable consists of dividing [the determinant of the coefficient matrix with its n-th column replaced with the right side of the system, the numbers in boldface,] by [the determinant of the coefficient matrix].

Compute each determinant:

[tex]\begin{vmatrix}\mathbf 3&-3&7\\\mathbf 0&2&-1\\\mathbf 3&-2&0\end{vmatrix}=3\begin{vmatrix}2&-1\\-2&0\end{vmatrix}+3\begin{vmatrix}-3&7\\2&-1\end{vmatrix}=3(0-2)+3(3-14)=-39[/tex]

(expanding along the first column)

[tex]\begin{vmatrix}0&\mathbf 3&7\\1&\mathbf 0&-1\\5&\mathbf 3&0\end{vmatrix}=-1\begin{vmatrix}3&7\\3&0\end{vmatrix}+5\begin{vmatrix}3&7\\0&-1\end{vmatrix}=-1(0-21)+5(-3-0)=6[/tex]

(again, along the first column)

[tex]\begin{vmatrix}0&-3&\mathbf 3\\1&2&\mathbf 0\\5&-2&\mathbf 3\end{vmatrix}=-1\begin{vmatrix}-3&3\\-2&3\end{vmatrix}+5\begin{vmatrix}-3&3\\2&0\end{vmatrix}=-1(-9-(-6))+5(0-6)=-27[/tex]

(first column)

So, we get the solution

[tex]x_1=\dfrac{-39}{-69}=\boxed{\dfrac{13}{23}},x_2=\dfrac6{-69}=\boxed{-\dfrac2{23}},x_3=\dfrac{-27}{-69}=\boxed{\dfrac9{23}}[/tex]

(c) Using elimination:

- 3 x₂ + 7 x₃ = 3

x₁ + 2 x₂ - x₃ = 0

5 x₁ - 2 x₂ = 3

Swap the first two equations:

x₁ + 2 x₂ - x₃ = 0

- 3 x₂ + 7 x₃ = 3

5 x₁ - 2 x₂ = 3

Add -5(equation 1) to equation 3:

x₁ + 2 x₂ - x₃ = 0

- 3 x₂ + 7 x₃ = 3

- 12 x₂ + 5 x₃ = 3

Add -4(equation 2) to equation 3:

x₁ + 2 x₂ - x₃ = 0

- 3 x₂ + 7 x₃ = 3

- 23 x₃ = -9

Multiply through equation 3 by -1/23:

x₁ + 2 x₂ - x₃ = 0

- 3 x₂ + 7 x₃ = 3

x₃ = 9/23

Add -7(equation 3) to equation 2:

x₁ + 2 x₂ - x₃ = 0

- 3 x₂ = 6/23

x₃ = 9/23

Multiply through equation 2 by -1/3:

x₁ + 2 x₂ - x₃ = 0

x₂ = -2/23

x₃ = 9/23

Add -2(equation 2) and equation 3 to equation 1:

x₁ = 13/23

x₂ = -2/23

x₃ = 9/23

Will give brainliest if correct what is the discriminant of the quadratic equation: (multiple choice)

Answers

Answer:
The discriminant is 60

What is the opposite of the opposite of -1.4?​

Answers

Answer:

-1.4

Step-by-step explanation:

opposite of -1.4 = 1.4

opposite of the opposite of -1.4 = the opposite of 1.4 = -1.4

-1.4 djkendnennd!;&2!;&2!;!2!!;

I need help with a math problem comment if u want i really need help with this

Answers

What is the math problem? I’ll try to answer it

Solve: x^2=10
A) x= +5
B) x= +100
C) x= +3.5
D) x= 10 squared

Answers

Answer:

D) x=√10

Step-by-step explanation:

√(10)=3.16(approximately )

Gwendolyn was physically present in the United States for 96 days in 2019, 198 days in 2018, and 66 days in 2017. Under the substantial presence test formula, how many days is Gwendolyn deemed physically present in the United States in 2019 g

Answers

Answer:

173 days

Step-by-step explanation:

The formula for substantial presence test is;

SBT = (Total of number of days present in the current tax year) + (1/3)(number of days in the year that was before the tax year) + (1/6)(number of days in the year that was two years before the tax year)

From the question, present tax year is 2019 and number of days is 96 days.

Year before tax year is 2018 and number of days is 198 days

2 years before tax year is 2017 and number of days is 66 days.

Thus;

SBT = 96 + ((1/3)198) + ((1/6)66)

SBT = 173 days

Suppose after 2500 years an initial amount of 1000 grams of a radioactive substance has decayed to 75 grams. What is the half-life of the substance? The half-life is:_______.
(A) Less than 600 years
(B) Between 600 and 700 years
(C) Between 700 and 800 years
(D) Between 800 and 900 years
(E) More than 900 years

Answers

Answer:

The correct answer is:

Between 600 and 700 years (B)

Step-by-step explanation:

At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:

[tex]A(t) = A_0 e^{(kt)}\\where:\\A(t) = Amount\ left\ at\ time\ (t) = 75\ grams\\A_0 = initial\ amount = 1000\ grams\\k = decay\ constant\\t = time\ of\ decay = 2500\ years[/tex]

First, let us calculate the decay constant (k)

[tex]75 = 1000 e^{(k2500)}\\dividing\ both\ sides\ by\ 1000\\0.075 = e^{(2500k)}\\taking\ natural\ logarithm\ of\ both\ sides\\In 0.075 = In (e^{2500k})\\In 0.075 = 2500k\\k = \frac{In0.075}{2500}\\ k = \frac{-2.5903}{2500} \\k = - 0.001036[/tex]

Next, let us calculate the half-life as follows:

[tex]\frac{1}{2} A_0 = A_0 e^{(-0.001036t)}\\Dividing\ both\ sides\ by\ A_0\\ \frac{1}{2} = e^{-0.001036t}\\taking\ natural\ logarithm\ of\ both\ sides\\In(0.5) = In (e^{-0.001036t})\\-0.6931 = -0.001036t\\t = \frac{-0.6931}{-0.001036} \\t = 669.02 years\\\therefore t\frac{1}{2} \approx 669\ years[/tex]

Therefore the half-life is between 600 and 700 years

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