15. The mean number of travel days per year for salespeople employed by hardware distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot study the mean was 150 days and the standard deviation was 14 days. If the population mean is estimated within two days, how many salespeople should be sampled?
Answer
134
452
511
2100
2 . If university officials say that at least 70% of the voting student population supporting the fee increase, If the 95% confidence interval is [0.75, 0.85], what conclusion can be drawn based on a 95% level of confidence?
Answer
70% is not in the interval, need to take another sample
70% is not in the interval, so assume it will not be supported
70% is below the interval, so assume it will be supported
Since this was not based on population, cannot make conclusion
3 . It is claimed that in a bushel of peaches less than ten percent are defective. A sample of 400 peaches is examined and 50 are found to be defective. What is the z-statistic?
Answer
0.025
0.278
-1.65
1.67