Question

On the first day of​ June, there were about 17.71 h of daylight in a city. Five months​ later, there were about 5.30 h of daylight. What was the percent​ decrease?

Answer 1

Percentage increases and decreases, are found by setting the problem up proportionally.

You are trying to find what percentage of 17.37 is 8.30 first.

so What %/100 = 8.30/17.37

Now define a variable:

Let x = What%

x/100 = 8.30/17.37

17.37x = 830

x = 830/17.37

x ≈ 47.78

8.30 is approximately 47.78% of 17.37, so the percentage decrease is 100% - 47.78% = 52.22%

The percentage decrease is approximately 52.22%