Construct a 90 percent confidence interval for the proportio

Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back. (Do not round the intermediate answers. Round your answers to 4 decimal places.)

Of 43 bank customers depositing a check, 18 received some cash back.

p=18/43 = 0.4186047

Given a=1-0.9=0.1, Z(0.05) = 1.645 (from standard normal table)

So the lower bound is

p - Z*sqrt(p*(1-p)/n) =0.4186047 -1.645*sqrt(0.4186047*(1-0.4186047)/43) =0.2948

So the upper bound is

p + Z*sqrt(p*(1-p)/n) =0.4186047 +1.645*sqrt(0.4186047*(1-0.4186047)/43) =0.5424

Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back. (Do not round the intermediate answers. Round your answer

Construct a 90 percent confidence interval for the proportio

Solution

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