Question

Suppose that the compressive strength of concrete is normally distributed with an unknown mu and a...

Suppose that the compressive strength of concrete is normally distributed with an unknown

mu and a known sigma of 40 (pounds per square inch). A random sample of size 19 has sample

mean 1376. Construct a 92% confidence interval (as crazy and unlikely as it seems to create

a 92% CI) for the population mean. Give answer to one decimal place.

Math   Statistics-And-Probability   
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Homework Answers

Answer #1

Solution :

Given that,

Z/2 = 1.75

Margin of error = E = Z/2* ( /n)

= 1.75 * (40 / 19)

= 16.1

At 92% confidence interval estimate of the population mean is,

- E < < + E

1376 - 16.1 < < 1376 + 16.1

1359.9 < < 1392.1

(1359.9 , 1392.1)

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