The rainfall total two years ago was 10.2inches. Last year’s total was 20% greater. What was last year’s rainfall total? *

Answer 1

Good afternoon Yareli

This problem focuses on the usage of percentages and percent change.

two_years_ago = 10.2 inches

Conceptually there is a percent increase of 20% from two years ago. This means that you will be able to add 100% of that past rain fall total to 20% of that past rain fall total.

Here is a worked out solution...

last_year = two_years_ago + two_years_ago*.2 = 1.2*two_years_ago

plug in rainfall total of two_years_ago variable

last_year = 1.2*10.2 = 12.24 inches total rainfall

Answer 2

10.2 + 20% of 10.2

= 10.2 + 2.04 = 12.24 inches

Answer 3

To find amount that is 20% greater, take amount from 2 years ago, 10.2 inches, and add 20% of 10.2 inches:

10.2 + 20% of 10.2

20% is 0.20 in decimal and "of" translates to multiplication, so

10.2 + 0.2 * 10.2 = 10.2 + 2.04 = 12.24 inches