Name:
:
Group (circle one): 1 2
Intro-Stat, Math 203 B, Candy bar Quiz 4
Tom Linton, March 31, 2000
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Random samples are drawn from a quantitative population that is normally
distributed with unknown mean m and a standard
deviation s =10.
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One sample of size n = 6 has mean
= 98.7. Give a 98% confidence interval for the population mean based on
this sample.
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Describe what your interval from part (a) tells you about the population
mean m.
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If in part (a), the mean value
= 98.7, came from a sample of size n = 20 (instead of n = 6), would the
corresponding 98% confidence interval for m
be bigger (wider or longer) or smaller? Explain.
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Would a 90% confidence interval (based on the same sample as in part a)
be wider or narrower than the 98% confidence interval from part (a)?
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If you wanted a 98% confidence interval for m
to have a margin of error equal to 0.05, how large would your sample size,
n, have to be?
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An SRS of size n = 12 sixth-grade boys go bowling and obtain the scores
shown below:
Bowling Scores
| 100 |
93 |
83 |
119 |
104 |
92 |
113 |
100 |
111 |
111 |
86 |
89 |
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Make a stem and leaf plot of the 12 scores.
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Are there any severe outliers or do the 12 scores exhibit extreme skewness?
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Suppose that the standard deviation of bowling scores for all 6th-grade
boys is s = 12. Calculate a 95% confidence interval
for the mean bowling score of 6th-grade boys, based on the sample above.
-
Suppose that the standard deviation of bowling scores for all 6th-grade
boys is s = 12. Calculate a 90% confidence interval
for the mean bowling score of 6th-grade boys, based on the sample above.