0805 0568 0195 0043 0805 0568 0195 0043 The average age of r

0.805.

0.568.

0.195.

0.043.

		0.805.
		0.568.
		0.195.
		0.043.

The average age of residents in a large residential retirement community is 69 years with standard deviation 5.8 years. A simple random sample of 100 residents is to be selected, and the sample mean age of these residents is to be computed. The probability that the average age, of the 100 residents selected is less than 68.5 years is

Solution

So the probability is

P(xbar<68.5) = P((xbar-mean)/(s/vn) <(68.5-69)/(5.8/sqrt(100)) )

=P(Z<-0.86)

=0.1949 (from standard normal table)

Answer: 0.195