A certain brand of automobile tire has a mean life span of 32,000 miles and a standard deviation of 2,450 miles.​ (Assume the life spans of the tires have a​ bell-shaped distribution.) ​(a) The life spans of three randomly selected tires are 34,000 ​miles, 37,000 ​miles, and 31,000 miles. Find the​ z-score that corresponds to each life span.

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Answer:

a)

The z-score corresponds to 34000 is 0.816

The z-score corresponds to 37000 is 2.041

The z-score corresponds to 31000 is -0.408

Step-by-step explanation:

The z-score corresponds to 34000

Let x=34000

z-score=(x-mean)/standard deviation

z-score=34000-32000/2450=0.816

The z-score corresponds to 34000 is 0.816

The z-score corresponds to 37000

Let x=37000

z-score=(x-mean)/standard deviation

z-score=37000-32000/2450=2.041

The z-score corresponds to 37000 is 2.041

The z-score corresponds to 31000

Let x=31000

z-score=(x-mean)/standard deviation

z-score=31000-32000/2450=-0.408

The z-score corresponds to 31000 is -0.408