1. A real estate expert claimed the current mean value of houses in a particular area
was more than $250,000. Find the confidence interval at 95% level of the
following cases:
a) A random sample of 13 recent sales prices in the area yielded a sample mean of
$265,000, it is known that house values in the area are approximately
normally distributed with a standard deviation of $50,000.
b) A random sample of 13 recent sales prices in the area yielded a sample mean
of $265,000, it is known that house values in the area are approximately
normally distributed and house values of these 13 sales has a standard
deviation of $50,000.
c) A random sample of 150 recent sales prices in the area yielded a sample mean
of $265,000, it is known that house values of these 150 sales have a standard
deviation of $50,000.
d) A random sample of 150 recent sales prices in the area yielded a sample mean
of $265,000, it is known that house values in this area have a standard
deviation of $50,000.