Question

The set of life spans of an appliance is normally distributed with a mean

months. What is the life span of an appliance that has a z-score of -3?

= 48 months and a standard deviation o = 8

3 months

24 months

45 months

72 months

Answer 1

24 months

Explanation:

Answer 2

24 months

Explanation:

Lifespan with z-score of -3 in the the set of normally distributed life spans of an appliance can be calculated using the equation:

`z=(X-M)/(s)` where

• X is the lifespan we are looking for

• M is the mean life span of the appliance (48 months)

• s is the standard deviation of the distribution of the life spans (8 months)

We have
`-3=(X-48)/(8)` that is

-24=X-48 and

X=24 months.

The life span of an appliance that has a z-score of -3 is 24 months.