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

The probability that the selected battery will have a life span of at most 2.1 hours is 5.48%.

z score is used to determine by how many standard deviations the raw score is above or below the mean. It is given by:

$z=\frac{x-\mu}{\sigma} \\\\where\ x\ is\ raw\ score, \mu\ is\ mean,\sigma\ is\ standard \ deviation$

Given that μ = 2.5, σ = 0.25.

For x < 2.1:

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

From the normal distribution table, P(x ≤ 2.1) = P(z < -1.6) = 0.0548 = 5.48%

The probability that the selected battery will have a life span of at most 2.1 hours is 5.48%.

Find out more on z score at: brainly.com/question/25638875