Question

A marketing manager needs to estimate the true mean dollar amount spent by members of Amazon Prime to determine if targeted advertising efforts for the service at the point of checkout should be adjusted to reflect a difference in mean spending from previous amounts. She obtains the following sample statistics from a sample of 100 Amazon Prime members who recently made a purchase: n 100 top enclose y 1400 s 250 Using this information, she she can be 98% confident that the true mean amount spent is between $ and $ . Enter your answers to the nearest whole dollar amount.

Answer 1

df = n -1 = 100 - 1 = 99

t critical value at 0.02 significance level with 99 df = 2.365

98% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

1400 - 2.365 * 250 / sqrt(100) < < 1400 + 2.365 * 250 / sqrt(100)

1341 < < 1459

he can be 98% confident that the true mean amount spent is between $1341 and $1459