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.
B because there is only one negative and -63 divided by 7 equals -9. If it were -7 divided by 63 that would give you an answer in decimal form.
Ok, to solve this first you have to set up your proportion:
9/150=x/230
/ is a fraction
x= the number of vials it will take to treat 230 patients
in order to solve this, you have to cross multiply:
9 x 230= 2070
150 · x= 150x
so you get 150x=2070
then divide 2070 by 150
2070/150= 13.8
so it would take 13.8 vials of medicine to treat 230 patients
A = 10
Step by step
3+7=10
10+(-7)=3
