Sample Size level One-tailed or two-tailed t* z* 3 0.05 Two-tailed 4.3 1.96 7 0.
ID: 3174933 • Letter: S
Question
Sample Size
level
One-tailed or two-tailed
t*
z*
3
0.05
Two-tailed
4.3
1.96
7
0.01
One-tailed
3.14
2.33
10
0.10
One-tailed
1.37
1.28
17
0.01
One-tailed
2.58
2.33
30
0.10
Two-tailed
1.70
1.28
101
0.05
Two-tailed
1.98
1.96
1. Find the values of the t-distribution that bound the middle 0.95 of the area under the curve for the distribution with df = 20. (2 points)
2.Ten randomly selected teenagers were each asked to list how many hours they watched TV per week. The results are: 23, 54, 19, 33, 27, 45, 8, 26, 43, and 18.
a) Determine the 95% confidence interval estimate for the mean number of hours of television watched per week by teenagers. Assume the number of hours is normally distributed. (4 points)
b) Discuss how this situation does or does not satisfy the assumption for inference? (2 points)
Sample Size
level
One-tailed or two-tailed
t*
z*
3
0.05
Two-tailed
4.3
1.96
7
0.01
One-tailed
3.14
2.33
10
0.10
One-tailed
1.37
1.28
17
0.01
One-tailed
2.58
2.33
30
0.10
Two-tailed
1.70
1.28
101
0.05
Two-tailed
1.98
1.96
Explanation / Answer
Here, mean = 29.6 , std. deviation = 14.14 , n =10
a)
z value for 95% confidence interval = 1.96
Standard error = s / sqrt(n)
= 14.14 / sqrt(10)
= 4.47
CI = mean + / - Z * SE
= 29.6 + / - 1.96 * 4.47
= (20.833, 38.366)
Lower Limit = 20.833
Upper limit = 38.366
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