Question

The lifetime of a certain type of battery is normally distributed with a mean of 1000 hours and a standard deviation of 100 hours. Find the probability that a randomly selected battery will last between 950 and 1050 hours

Answer 1

This is a normal distribution question with

x₁ = 950
x₂ = 1050
P(950.0 < x < 1050.0)=?

This implies that
P(950.0 < x < 1050.0) = P(-0.5 < z < 0.5) = P(Z < 0.5) - P(Z < -0.5)
P(950.0 < x < 1050.0) = 0.6914- 0.3085
P(950.0 < x < 1050.0) = 0.3829
PS: you have to refer z score table to find the final probabilities.
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