A local bus company is planning a new route to serve four housing subdivisions. Random samples of households are taken from each subdivision, and sample members are asked to rate, on a scale of 1 (strongly opposed) to 5 (strongly in favor), their reaction to the proposed service. The results are summarized in the accompanying table.

a. Find a 90% confidence interval for the mean reaction of households in subdivision 1.
b. Using an unbiased estimation procedure, estimate the mean reaction of all households to be served by the new route.
c. Find 90% and 95% confidence intervals for the mean reaction of all households to be served by the new route.

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Subdivision 1 240 40 Subdivision 2 190 40 3.6 0.9 Subdivision 3 350 40 3.9 1.2 Subdivision 4 280 40 2.8 0.7 Mi T 2.5 0.8