A sample of 20 randomly chosen water melons was taken from a large population, and their weights were measured. The mean weight of the sample was lb. and the standard deviation was S =15 lb.

Construct a 90% confidence interval for the mean weight of the whole population of water melons.












(B) A survey of families having kids at school showed that 372 of 1,200 sampled families attended a parents meeting during the year. Using the 90% level of confidence, what is the confidence interval for the proportion of families attended a parents meeting?