If the average grade of an english class rose from 70 to 85, what is the approximate percent increase?

answer choices

the percent increase is 14%.
the percent increase is 17%.
the percent increase is 21%.
the percent increase is 35%.

85 - 70 = 15

15/70 = 0.21428571428

Round to .21

Move decimal over twice to the right

21%

The percent increase is 21%.

Step-by-step explanation:

Given,

The original average grade = 70,

New average grade = 85,

Total changes in the average grade = New average grade - original average grade

= 85 - 70

= 15

Since,

⇒ The approximate percent increase is 21 %.