A sample of size 100 was taken from the population represented in Figure 15-1. The results showed that
= 0.52
s2 = 2.62
a. Determine a 90 percent interval estimate for μ. (Recall from Figure 15-1 that σ = 1.49.)
b. Determine a 95 percent interval estimate for μ.
c. Repeat (a) and (b) using s2 instead of σ2.
d. What sample size would be needed to reduce the sampling error to 0.10 if a confidence level of 95 percent were desired? Use the fact that σ = 1.49.

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Scale Description Frequency Percentage Extremely important 4 Important Desirable 5,000 8,000 6,000 2 Only a small plus 2,000 Of no consequence 4,000 25,000 20 32 24 8 16 100 3