Question

James is training for a marathon. Every week, he increases the distance he runs by 15%. If James is running 8.5 miles this week, how far will he be running 2 weeks from now?

I did 30/100=x/8.5 . I thought that if I did 30 (for 2 weeks) instead of 15 (1 week) I could get a straight answer. But the answer choices I have are:

A. 15.3 miles. B. 10.2 miles
C. 11.24 miles. D. 9.8 miles

Answer 1

The problem says that he increases the distance he runs by 15%, not by 15 miles.
First, we get how much distance is increased in the first week, by getting the 15% of the original distance he can cover:
15% of 8.5 can be translated mathematically to
0.15 x 8.5
which is equal to 1.275
The 1.275 miles is the increase in distance he can cover. Therefore,
8.5 miles (original) + 1.275 miles (increase) = 9.775 miles

For the second week, we'll do the same, but instead of 15% of 8.5, we'll solve for 15% of the previous week, which is 9.775:
0.15 x 9.775 = 1.46625
Thus,
9.775 miles (first week) + 1.46625 miles (increase) = 11.24125 miles
We can round it off to two decimal places to become 11.24 miles.

hope this helps~ `u`

Answer 2

for the first week, he will run a total of x=(8.5*.15) + 8.5. So the answer for the first week is 9.775. for the second week, he will run 15% more of the 9.775 miles. So it will become x=(9.775*.15)+ 9.775. And the answer is letter c.

Answer 3

distance now = 8.5
one week from now = 8.5(1.15)
two weeks from now = 8.5(1.15)^2 = 11.24