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

Percentage error is calculated by

Percentage error = (estimate-real)/real*100%=(115-82.5)/82.5*100%=28.26%

An over-estimate gives a positive error percent, and an underestimate gives a negative error.

Also, dividing by the real value makes it possible to have more than 100% error.

For example, if real cost is $50, and estimated cost is $150, then error percent is (150-50)/50*100%=200%!

Answer 2

Answer: C: 39.4%

Step-by-step explanation:

The formula to calculate the percent error is given by :-

$\text{Percent error}=\dfrac{|\text{Estimated value - Actual value}|}{\text{Actual value}}\times100$

Given: The estimated amount = $115

The actual amount = $ 82.50

Now,  the percent of error will be given by :-

$\text{Percent error}=\dfrac{|115-82.50|}{82.50}\\\\\Rightaarrow\text{Percent error}\times100=\dfrac{32.50}{82.50}\times100\\\\\Rightaarrow\text{Percent error}\times100=39.3939393939\approx39.4\%$