Question 8
Your answer is CORRECT.
An experimenter flips a coin 100 times and gets 51 heads. Find the 85% confidence interval for the
probability of flipping a head with this coin.
a)
[0.430, 0.390]
b)
[0.430, 0.590]
c)
[0.480, 0.485]
d)
[0.330, 0.540]

12/8/13 4:53 PM
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e)
[0.350, 0.590]
f)
None of the above
Question 9
Your answer is CORRECT.
Suppose that prior to conducting a coin-flipping experiment, we suspect that the coin is fair. How many
times would we have to flip the coin in order to obtain a 96.5% confidence interval of
width
of at most
.17 for the probability of flipping a head?

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Question 10
Your answer is CORRECT.
It has been observed that some persons who suffer acute heartburn are diagnosed with it again within one
year of the first episode. This is due, in part, to damage from the first episode. In order to examine the
percentage of the persons who suffer acute heartburn a second time, a random sample of 1100 people who
suffered acute heartburn was collected. It was observed that 17 of them again suffered acute heartburn
within one year. Select a 99% confidence interval for the true proportion of those who suffer a second
episode.

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Page 6 of 8
f)
None of the above