Of 58 bank customers depositing a check, 15 received some cash back. (a) Construct a 90 percent confidence interval for the proportion of all depositors who ask for cash back. (Round your answers to 4 decimal places.)

0.1640 ≤ p ≤0.3532

Explanation:

Sample size (N) = 58 customers

Z-score for 90% interval (Z) = 1.645

The proportion of customers that received some cash back is given by:

The confidence interval for the proportion of all depositors who ask for cash back is determined by the following relationship:

Applying the given data:

The upper and lower limits are:

Using a 90% confidence level, the interval for the proportion (p) is:

0.1640 ≤ p ≤0.3532