Suppose that a committee is studying whether or not there is waste
of time in our judicial system. It is interested in the mean amount of
time individuals waste at the courthouse waiting to be called for jury
duty. The committee randomly surveyed 81 people who recently served as
jurors. The sample mean wait time was eight hours with a sample
standard deviation of four hours.

a.

x -bar =____

Sx=

n=___

n-1 = ____

b. Define the random variables X and X (with a line over top of it)

c. Which distribution should use you for this problem?

d. Construct a 95% confidence interval for the population mean time wasted. State the confidence interval

x-bar is the sample mean which is 8

Sx is the standard deviation of x which is 4

n = sample size of 81

n-1 is the degrees of freedom which is 80

part b, x is the time an individual waited to be called for jury duty
and x-bar is the sample mean, so that is the mean waiting time

c) this is t-distribution since population standard deviation is not known

part d, 95% CI, for 80 df, t value is 1.99

8 +/- 1.99(4/sqrt(81))

8 +/- 0.88 = (7.12, 8.88)

the error bound is also known as the margin of error which is the
value added and subtract from the mean in the interval which is 0.8

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