Question

Its winter and the powder on Vail Mountain has never been better. You decide to measure the snowfall over a three hour period to determine the amount of snow that has fallen. The first hour you record a 5% increase in snowfall, the second hour you record a 8% increase in snowfall, and the third hour you record a 11% increase in snow fall. Over the three hour period, the snow has increased to a height of 17 inches. How high was the snow on the first hour just before it started to snow? Round your answers to the nearest tenth of an inch.

Answer 1

Let's say you have $100.
Then you are given $20.
Your new total is $120.
How much percent did your original amount go up by from $100 to $120?
Since $20 is 20% of $100, it went up 20%.

Answer 2

Now think of your final amount, $120.
You are told you have $120 now which is an increase of 20% over what you used to have. How much did you have before?
Since the total amount is 100%, and with a 20% increase you get 120%, and 120% = 1.20, just divide $120 by 1.2 to find the originakl amount of $100.

Answer 3

The bottom line is if you are given an amount and are told that is an increase of x% over what it used to be, add x% to 100%, write it as a decimal, and divide the new amount by that number to find the original number.

Answer 4

For example:
300 is a 50% over an amount. What is the amount?
Solution: 300/1.50 = 200
The original amount was 200.