The time required to complete a statistics final exam is normally distributed, w

Question

The time required to complete a statistics final exam is normally distributed, with a mean of 152 minutes and a standard deviation of 18.5 minutes. If a sample of 22 students are randomly selected, find the probability that their mean time to finish the FINAL will be between 140 and 170 minutes A recent study of 40 students showed that they spent an average of $41.50 for gasoline per week. The stand deviation of the population is assumed to be $3.36. Find the 95% confidence interval of the true mean mu.

Explanation / Answer

Solution:-

2)

95% confidence interval is for the true mean is C.I = (40.46, 42.54)

C.I = xbar + zalpha/2 × S.E

S.E = s / sqrt(n)

S.E = 0.531

C.I = 41.50 + 1.96 × 0.531

C.I = 41.50 + 1.0412

C.I = (40.46, 42.54)

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