Question

The life span of a battery is the amount of time the battery will last. The distribution of life span for a certain type of battery is approximately normal with mean 2.5 hours and standard deviation 0.25 hour. Suppose one battery will be selected at random. Which of the following is closest to the probability that the selected battery will have a life span of at most 2.1 hours?

Answer 1

Answer:

0.0548

Step-by-step explanation:

The distribution of life span for a certain type of battery is approximately normal with mean 2.5 hours and standard deviation 0.25 hour.

To find the the probability that a selected battery will have a life span of at most 2.1 hours, we need to first determine the z-score for x=2.1 hours using

$z = \frac{x - \mu}{ \sigma}$

We substitute the values to get:

$z = \frac{2.1 - 2.5}{0.25} = - 1.6$

We read read -1.6 from the standard normal distribution table to get:

P(X≤2.1)=0.0548