Question

In: Statistics and Probability

A manufacturer produces widgets whose lengths are normall distributed with a mean of 8 cm and...

A manufacturer produces widgets whose lengths are normall distributed with a mean of 8 cm and standard deviation of 3.9 cm.
A. If a widget is selected at random, what is the probability it is greater than 7.7 cm?
B. What is the standard deviation of the average of samples of size 39?
C. What is the probability the average of a sample of size 39 is greater than 7.7 cm?

Solutions

Expert Solution

X : length of widgets

X ~ N(8,3.9)

a).If a widget is selected at random,the probability it is greater than 7.7 cm be:-

[ in any blank cell of excel type =NORMSDIST(0.077) press enter]

b).the standard deviation of the average of samples of size 39 be:-

C.the sample mean will follow normal distribution with mean = 8 , standard deviation = 0.6245

the probability the average of a sample of size 39 is greater than 7.7 cm be:-

[ in any blank cell of excel type =NORMSDIST(0.4804) press enter]

*** if you have any doubt regarding the problem please write it in the comment box.if you are satisfied please give me a LIKE if possible...

orchestra answered 2 years ago
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