QUESTION 7

a) Sample of two different models of cars were selected, and the actual speed for each car was determined when the speedometer registered 50 mph. The resulting 95% confidence intervals for mean actual speed were (50.3, 52.7) and (49.8, 50.6) respectively. Assuming that the two sample standard deviations are equal, which confidence interval is based on the larger sample size? Explain your reasoning. 

(b) Three different statistics are being considered for estimating a population characteristic. The sampling distributions of the three statistics are shown in Figure 1. Which statistic would you recommend? Explain your choice.

(c) A manufacturer conducted a survey among 500 randomly selected target market households in the test market for its new disposable diapers. The objective of the survey was to determine the market share for its new brand. If the sample point estimate for market share is 15%, develop a 90% confidence interval. 

Statistic II Statistic II Statistic I True value of population characteristic Figure 1