Question

A manufacturer produces widgets whose lengths are normally distributed with a mean of 6.8 cm and standard deviation of 2.1 cm.

Round answer to four decimal places

A. If a widget is selected at random, what is the probability it is greater than 6.8 cm.?_____

B. What is the standard deviation of the average of samples of size 36 ?______

C. What is the probability the average of a sample of size 36 is greater than 6.8 cm?_______

Answer 1

This is a normal distribution question with

a) P(x > 6.8)=?

The z-score at x = 6.8 is,

z = 0.0

This implies that

P(x > 6.8) = P(z > 0.0) = 1 - 0.5

b)

c)

P(x > 6.8)=?

The z-score at x = 6.8 is,

z = 0.0

This implies that

P(x > 6.8) = P(z > 0.0) = 1 - 0.5

PS: you have to refer z score table to find the final probabilities.

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