Question

A random sample of 20 statistics examinations was taken. The average score, in the sample, was...

A random sample of 20 statistics examinations was taken. The average score, in the sample, was 84 with a standard deviation of 3.5. Develop a 95% confidence interval for the average examination score of the population of the examinations.

a. The critical value for the confidence interval   (Provide 3 decimals)

b. Lower limit   (Provide 2 decimals)

c. Upper limit   (Provide 2 decimals)

Math   Statistics-And-Probability   
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Homework Answers

Answer #1

Solution :

Given that,

a.

t /2,df = 2.093

Margin of error = E = t/2,df * (s /n)

= 2.093 * (3.5 / 20)

Margin of error = E = 1.64

The 95% confidence interval estimate of the population mean is,

- E < < + E

84 - 1.64 < < 84 + 1.64

82.36 < < 85.64

b. Lower limit: 82.36

c. Upper limit 85.64

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