Question

The set of lifespans of an appliance is normally distributed with a mean of 48 months and a standard deviation of eight months. What is the lifespan of an appliance that has a Z score of -3?

Answer 1

24 months

Explanation:

Given :

Mean = 48

Standard deviation = 8

Zscore = - 3

Using the relation :

Zscore = (x - mean) / standard deviation

Where, x = score

-3 = (x - 48) / 8

-3 * 8 = x - 48

-24 = x - 48

-24 + 48 = x

24 = x

Score = 24