Question

*round to nearest whole number*

14. Weights of Minivans The average weight of 40 ran- domly selected minivans was 4150 pounds. The popula- tion standard deviation was 480 pounds. Find a point es- timate of the population mean. Find the 99% confidence interval of the true mean weight of the minivans.

Answer 1

14)

Solution :

Given that,

Z_$\alpha$/2 = 2.576

Margin of error = E = Z_$\alpha$/2* ($\sigma$ /$\sqrt$n)

= 2.576 * (480 / $\sqrt$ 40)

= 196

At 99% confidence interval estimate of the population mean is,

$\bar x$ - E < $\mu$ < $\bar x$ + E

4150 - 196 < $\mu$ < 4150 + 1963

3954 < $\mu$ < 4346

(3954 , 4346)