Question

A photocopy machine can reduce copies to 80% of their original size. By copying an already reduced copy, further reductions can be made. (a) if a page is reduced to 80%, what percent enlargement is needed to return it to its original size? W incorrect: your answer is incorrect. Seenkey 125 % (b) estimate the number of times in succession that a page must be copied to make the final copy less than 15% of the size of the original. W incorrect: your answer is incorrect. Seenkey 9 time

Answer 1

Part a) if a page is reduced to 80%, what percent enlargement is needed to return it to its original size?

Let

x---------> the percent enlargement

we know that

the original size is the 100%

so

x*80%=100%

x=(100%/80%)

x=1.25--------> 1.25=(125/100)=125%

therefore

the answer Part a) is

the percent enlargement is 125%

Part b) Estimate the number of times in succession that a page must be copied to make the final copy less than 15% of the size of the original

we know that

A photocopy machine can reduce copies to 80% of their original size

so

Copy N 1

0.80*100%=80%

Copy N 2

0.80*80%=64%

Copy N 3

0.80*64%=51.2%

Copy N 4

0.80*51.2%=40.96%

Copy N 5

0.80*40.96%=32.77%

Copy N 6

0.80*32.77%=26.21%

Copy N 7

0.80*26.21%=20.97%

Copy N 8

0.80*20.97%=16.78%

Copy N 9

0.80*16.78%=13.42%-------------> 13.42% < 15%

therefore

the answer Part b) is

the number of times in succession is 9