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:
[tex]z=\frac{x-\mu}{\sigma} \\\\where\ x\ is\ raw\ score, \mu\ is\ mean,\sigma\ is\ standard \ deviation[/tex]
Given that μ = 2.5, σ = 0.25.
For x < 2.1:
[tex]z=\frac{2.1-2.5}{0.25}=-1.6[/tex]
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: https://brainly.com/question/25638875
