An appliance dealer's website features the mean life expectancy values for major household appliances. a standard refrigerator's mean life expectancy is 18 years with a standard deviation of 2 years. what is the probability that your standard refrigerator will last between 12 and 20 years? express the probability as a percentage rounded to the nearest hundredth.

There is an 84% probability that your standard refrigerator will last between 12 and 20 years.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean and standard deviation , the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

A standard refrigerator's mean life expectancy is 18 years with a standard deviation of 2 years. This means that .

What is the probability that your standard refrigerator will last between 12 and 20 years?

This probability is the pvalue of Z when subtracted by the pvalue of Z when . So

X = 20

has a pvalue of 0.8413

X = 12

has a pvalue of 0.0014

This means that there is a 0.8413-0.0014 = 0.8399 = 0.84 = 84% probability that your standard refrigerator will last between 12 and 20 years.

sas (side angle side)

aa (angle angle)

sss(side side side)

sas find two sides with an angle in between

aa is finding two angles and the third will add up to 180

sss find all sides

step-by-step explanation: