In a survey of U.S. consumer intentions, 498 families in a random sample of 2500 indicated that they intended to buy a new car within a year. Construct a 95% confidence interval for the proportion of all U.S. families intending a new car purchase.
(a) Answer two ways:
(1) Using the usual formula (8-19).
(2) Using the simplified formula (8-21).
(b) If the sample P had been .40, would the error in (a2) have been greater?