Suppose the life of a particular brand of laptop battery is normally distributed with a mean of 8 hours and a standard deviation of 0.6 hours. What is the probability that the battery will last more than 9 hours before running out of power?
A) 0.0478
B) 0.4525
C) 0.9525
D) 1.6667

Question

Quizplus · Accepted Answer

We need to find the probability that the battery will last more than 9 hours. 
Using the z-score formula, we can standardize the data: 
z = (x - μ) / σ 
z = (9 - 8) / 0.6 
z = 1.67
Using a standard normal distribution table, we can find the probability that z is greater than 1.67, which is 0.0478. 
Therefore, the probability that the battery will last more than 9 hours is 0.0478 or approximately 0.05, which is closest to option A.

Suppose the Life of a Particular Brand of Laptop Battery