8) Listed below are time intervals (min) between eruptions of a geyser. Assume that the "recent" times are within the past few years, the "past" times are from around 20 years ago, and that the two samples are independent simple random samples selected from normally distributed populations. Do not assume that the population standard deviations are equal. Does it appear that the mean time interval has changed? Is the conclusion affected by whether the significance level is

0.10 or 0.01

Recent: 78 91 89 79 57 100 62 87 70 88 82 84 57 81 75 102 62

Past: 90 89 93 94 65 86 86 92 88 91 90 91

A: The null and alternative hypothesis?

Ho: u1=u2

H1: u2 u2

B: Calculate the test statistic:

t=

_{(round to two decimal places as needed.)}

C: P-value=