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## A telecommunications company wants to estimate the proportion of households that would purchase an additional telephone line if it were made available

A telecommunications company wants to estimate the proportion of households that would purchase an additional telephone line if it were made available at a substantially reduced installation cost. Data are collected from a random sample of 500 households. The results indicate that 155 of the households would purchase the additional telephone line at a reduced installation cost. Complete parts (a) and (b) below.

a. Construct a 95% confidence interval estimate for the population proportion of households that would purchase the additional telephone line.

b. The margin of error is = ____ ?

c. The critical value for the upper tail is __ ?

*d. How would the manager in charge of promotional programs concerning residential customers use the results in (a)?*

i. The manager can infer with 95% confidence that the population proportion of all households that would purchase an additional telephone line is somewhere in

this interval

ii. The manager can infer with 95% confidence that the proportion of households in the sample that would purchase an additional telephone line is somewhere in

this interval.

iii. The manager can infer that 95% of households would purchase an additional telephone line.

iv. The manager can infer that the true population proportion of households that would purchase an additional telephone line is somewhere in this interval 95% of the time.