SOLUTION: I have been at this (and others) for hours and I don't know how to solve this...please help... A substance's mass grows exponentially at a 4% hourly rate. If the initial quantit

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Question 769065: I have been at this (and others) for hours and I don't know how to solve this...please help...
A substance's mass grows exponentially at a 4% hourly rate. If the initial quantity has a mass of 100 grams, what will be the mass after 10 hours?
Answer by josgarithmetic(39623) About Me  (Show Source):
You can put this solution on YOUR website!
Trying to make this as simple as possible, starting with m grams, rate of growth is r in its decimal fraction form, in the first hour, the mass becomes:
m%2A%281%2Br%29
In 2 hours,---------m%2A%281%2Br%29%2A%281%2Br%29
In 3 hours, --------m%2A%281%2Br%29%281%2Br%29%281%2Br%29
..
In x hours, --------highlight%28m%2A%281%2Br%29%5Ex%29

Use that pattern. Your example uses m=100 and r=0.04 and x=10.
Mass after 10 hours will be highlight%28100%2A%281.04%29%5E10%29 grams.
highlight%28148%29 grams.


You could use log table if desired and then find antilog of the result.

2%2B10%2A0.01770
2.17
Most people these days use scientific calculators, so you're looking for highlight%2810%5E2.17=148%29.