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Unformatted text preview: ed. (Recall from section 4.4 that we can assume that the sampling distribution
of x is normal for values of n greater than 30.)
Examples:
1. Suppose your class is investigating the weights of Snickers 1ounce funsize candy bars to see if
customers are getting full value for their money. Assume that the weights are normally distributed with
standard deviation σ =.005 ounces. Several candy bars are randomly selected and weighed with
sensitive balances borrowed from the physics lab.
The weights are:
.95
1.02 .98
.97
1.05 1.01 .98
1.00
We want to determine a 90% confidence interval for the true mean, µ .
a. What is the sample mean?
b. Determine z * .
c. Determine the 90% confidence interval. (Show your work)
d. Write a sentence that explains the significance of the confidence interval. 2. A SRS of 16 seniors from HISD had a mean SATmath score of 500 and a standard deviation of 100.
We know that the population of SATmath scores for seniors in the district is approximately normally
distri...
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 Spring '08
 HAFEEZ

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