Two surveys are taken. One estimates the mean number of shots it takes to comple
ID: 3152902 • Letter: T
Question
Two surveys are taken. One estimates the mean number of shots it takes to complete a golf course is 86, while the other suggests it is 93. (a) Suppose the first survey had 16 subjects, a mean of 86, and a sample standard deviation of 5 shots. Find the 99% confidence interval for the true mean using this survey. (b) Suppose the second survey had 20 subjects, a mean of 93, and a sample standard deviation of 9 shots. Find the 99% confidence interval for the true mean using this survey. (c) Let's assume these two surveys are truly random and are not influenced by weather conditions or other confounding variables. What should we look for in data of the second sample to try to explain the difference in the means? [Hint: one word or one sentence]
Explanation / Answer
a)
alpha / 2 = 0.005 df = 15 t=2.947
I: 86 +/- 2.947 * 5 / srqt (16)
86 +/- 3.684
82.316 < miu < 89.684
b)
alpha / 2 = 0.005 df = 19 t = 2.861
I: 93 +/- 2.861 * 9 / srqt(20)
93 +/- 5.76
87.24 < miu < 98.76
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