Question

The set of life spans of an appliance is normally distributed with a mean y = 48 months and a standard deviation or

8 months. What is the z-score of an appliance that stopped working at 64 months?

Answer 1

The set of life spans of an appliance is normally distributed with a mean µ= 48 months and a standard deviation σ= 8 months. ... Thanh finds that his grade on the test has a z-score of -2.5. ... are normally distributed, and the probability that the city gets more than 43.2 inches of rain in a year is given by P(z≥1.5)=0.0668.

Step-by-step explanation:

Answer 2

Answer: z = 2

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Step-by-step explanation:

The raw score is x = 64, and we want to find its corresponding z score.

The mean and standard deviation are mu = 48 and sigma = 8 respectively.

The z score is...

z = (x-mu)/sigma

z = (64-48)/8

z = 16/8

z = 2

A z score of 2 means we're 2 standard deviations above the mean.

As the formula above implies, we find the difference from the raw score (x) to the mean (mu). Then we divide over sigma to find out how many sigma steps we have to take to go from mu to x.

A negative z score would indicate the raw score is below the mean.