Question

The original quantity is 20 and the new quantity is 15. Adam incorrectly says the percent decrease is about ​14.29%. What is the correct percent​ decrease? What error did Adam likely make when finding the percent​ decrease? The correct percent decrease is 25 25​%. What error did Adam likely​ make? A. divided the difference of the two quantities by the sum of the two quantities. B. divided the difference of the two quantities by the product of the two quantities. C. divided the difference of the two quantities by the new quantity. D. divided the new quantity by the original quantity.

Answer 1

Answer:

The answer to how much the percent decreased is 25%.

Step-by-step explanation:

First, how much is 15 out of 20?

The answer is 75%.

The total is 100% (20 in this case.)

100% - 75% = 25%.

The remaining amount is 25%, which is the amount the percent dropped.

(20 x 25% = 5)

20 - 5 = 15

I am pretty sure the answer is A, but I'm not 100% sure.

Answer 2

Answer: A. divided the difference of the two quantities by the sum of the two quantities.

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Explanation:

The difference of the quantities is 20-15 = 5

The sum of the quantities is 20+15 = 35

Dividing those results leads to 5/35 = 0.142857 which rounds to 0.1429

That converts to 14.29%

This is likely the path Adam took. This path is incorrect. The correct steps are shown below

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Difference = 20-15 = 5

Divide the difference over the original quantity

5/20 = 1/4 = 0.25 = 25%

We have a 25% decrease because the new quantity (15) is smaller than the old quantity (20)

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Here's another way to approach the problem

A = old value = 20

B = new value = 15

C = percent change

C = [ (B-A)/A ] * 100%

C = [ (15-20)/20 ] * 100%

C = (-5/20)*100%

C = -0.25*100%

C = -25%

The negative C value means we have a negative percent change, ie we have a percent decrease. So this is another way to get a 25% decrease.