=+10.66 Water samples are taken from water used for cooling as it is being discharged from a power plant into a river. It has been determined that as long as the mean temperature of the discharged water is at most 1508F, there will be no negative effects on the river ecosystem. To investigate whether the plant is in compliance with regulations that prohibit a mean discharge water temperature above 1508F, a scientist will take 50 water samples at randomly selected times and will record the water temperature of each sample. She will then use a z statistic z 5 x 2 150 s

1n to decide between the hypotheses H0

: m 5 150 and Ha

:

m . 150, where m is the true mean temperature of discharged water. Assume that s is known to be 10.