Question

Following are interest rates (annual percentage rates) for a 30-year-fixed-rate mortgage from a sample of lenders in a certain cityIt is reasonable to assume that the population is approximately normal.

4.327,4.461,4,547 4.468, 4.365 , 4.707, 4.842

Find the upper bound of the 99% confidence interval for the mean rate.

Round to three decimal places (for example : 4.015 ). Write only a number as your answer . Do not write any units ..

Answer 1

	x	(x-xbar)^2
	4.327	0.041616
	4.461	0.0049
	4.547	0.000256
	4.468	0.003969
	4.365	0.027556
	4.707	0.030976
	4.842	0.096721
Sum	31.717	0.205994

Mean(x)=xbar=sum(x)/n	4.531
standard deviation(s)=sum(x-xbar)^2/n-1	0.18529
n	7

for 99 % confidence level with degree of freedom (n-1)=6
c	0.1
degrres of freedom	6
t=critical value obtain using t-table with corresponding df=n-1	1.94318
Margin of error =t*s/sqrt(n)	0.136087
lower bound =xbar-ME	4.394913
upper bound =xbar+ME	4.667087

Upper bound=4.667

#  upper bound of the 99% confidence interval for the mean rate. is  4.667