Thread: Exponential functions

Hailey has begun a fitness program. The first week she ran 1 mile every day. Each week she increases the amount that she runs each day by 20%. In week 10, how many miles does she run each day? Give your answer to the nearest mile.

My solution:
A=P(1+r)^n
=1(1.2)^9
=5

Yes, that is correct. "To the nearest mile" isn't all that accurate but if that was what you were told to do ....

How come the answer key to the amsco textbook says it is 6 miles?

Originally Posted by victorwen28

How come the answer key to the amsco textbook says it is 6 miles?

because the individual who made the answer key erroneously calculated , which is the number of miles run each day in week 11.

So it is a guaranteed 5 miles?