The percent of a certain brand of computer chips that will fail after t years of use is estimated to be .

What percent of this brand of computer chips are expected to be usable after 6 years?

A) 71.3%
B) 56.7%
C) 69.9%
D) 64.2%

Question

The percent of a certain brand of computer chips that will fail after t years of use is estimated to be ​  .
​
What percent of this brand of computer chips are expected to be usable after 6 years?
​
A) 71.3% 
B) 56.7% 
C) 69.9% 
D) 64.2%

Quizplus · Accepted Answer

To find the percent of chips expected to be usable after 6 years, we need to subtract the percent of chips that will fail from 100% and then raise it to the 6th power (since we want to know what percent will still be working after 6 years). 
So, 100% - 11.4% = 88.6%
0.886^6 ≈ 0.300
Therefore, 30.0% of the chips are expected to be usable after 6 years, which is closest to choice C (69.9% of the chips will fail after 6 years, so 100% - 69.9% = 30.1% of the chips will still be usable).

The Percent of a Certain Brand of Computer Chips That