Question

In: Statistics and Probability

A simple random sample of 12 reaction times of helicopter pilots is selected. The reaction times...

A simple random sample of 12 reaction times of helicopter pilots is selected. The reaction times have a normal distribution. The sample mean is 1.67 sec with a standard deviation of 0.16 sec. Construct a 90% confidence interval for the population standard deviation.

1.

0.11 < σ < 0.23
2.

0.01 < σ < 0.05
3.

0.12 < σ < 0.25
4.

0.13 < σ < 0.22

Solutions

Expert Solution

Solution :

Given that,

s = 0.16

s2 = 0.0256

2L = 2/2,df = 19.675

2R = 21 - /2,df = 4.575

The 90% confidence interval for is,

(n - 1)s2 / 2/2 < < (n - 1)s2 / 21 - /2

  12 * 0.0256 / 19.675 < < 12 * 0.0256 / 4.575

0.12 < < 0.25

orchestra answered 2 years ago
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