Question

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

Answer 1

Answer:

24 months

Step-by-step explanation:

Answer 2

Answer:

24 months

Step-by-step 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:

$z=\frac{X-M}{s}$ 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 $-3=\frac{X-48}{8}$  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.