A recent survey described the sleep time of college students as normally distributed with a standard deviation of 1.15 hours and a mean of 7.02 hours. Suppose we wish t take a simple random sample of size 81 from the population of college students and examine the sleep time. Let X be he vector of 81 observation and let X ( x ahd bar on top) be the sample mean and s the sample standard deviation.
a) About what should be calculated sample mean of X be?
b) About what should be calculated sample standard deviation of X be?
c) What is the standard deviation of distribution of X ? ( x has bar on top)
d) About how many of the 81 students sleep less than 6 hours?
e) About how many of the 81 students sleeo between 6.52 and 7.52 hours.
f) What is the probability that X is below 6.9 hours? ( x has bar on top)