Question

A random sample of 10 funnel-eared bats yields a mean length of 4.8 cm. Lengths of these bats are known to be Normally distributed with standard deviation 1.2 cm. The upper end of the 90% confidence interval for the mean length of all funnel-eared bats is: (round to 1 decimal place)

Answer 1

90% Upper end confidence limit for $\mu$ is

$\bar{x}$ + Z$\alpha$/2 * $\sigma$ / Sqrt (n)

4.8 + 1.2816 * 1.2 / sqrt(10)

= 5.3

90% Upper end CI is (-$\infty$ , 5.3 )