Question

A manufacturer knows that their items have a normally distributed lifespan, with a mean of 10.3 years, and standard deviation of 2.6 years. If you randomly purchase one item, what is the probability it will last longer than 10 years?

Answer 1

This is a normal distribution question with

P(x > 10.0)=?

The z-score at x = 10.0 is,

z = -0.1154

This implies that

P(x > 10.0) = P(z > -0.1154) = 1 - 0.45406

P(x > 10.0) = {0.5459}

PS: you have to refer z score table to find the final probabilities.

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