Question

Erika calculated that she would spend $115 on school supplies this year. She actually spent $82.50 on school supplies. What is Erika’s percent of error?

a 28.3%
b 2.8%
c 39.4%
d 32.5%

Answer 1

The answer is actually C

Explanation:

This is because you do 115 - 82.50 = 32.5 then divide by 82.5 = 0.394 multiply by 100 = 39.4%. A lot of people use the theoretical number to divide instead of the actual, because people confuse the number 115 the theoretical number with the actual one. This causes people to use the number 115 to divide when you should use 82.5 to divide.

Answer 2

The equation to find percent error is:
percent error=(experimental-theoretical)/theoretical *100
So, (115-82.5)/82.5=0.393939*100
39.3939%, or 39.94%

Hope this helps!!