The method of tree ring dating gave the following years A.D. foran archaeological excavation site. Assume that the population of xvalues has an approximately normal distribution. 1285 1250 11871236 1268 1316 1275 1317 1275

(a) Use a calculator with mean and standard deviation keys tofind the sample mean year x and sample standard deviation s. (Roundyour answers to the nearest whole number.)

x = ____A.D.

s = _____yr

(b) Find a 90% confidence interval for the mean of all tree ringdates from this archaeological site. (Round your answers to thenearest whole number.)

lower limit A.D.

upper limit A.D.

________________________________________________________________________

How much does a sleeping bag cost? Let's say you want a sleepingbag that should keep you warm in temperatures from 20°F to 45°F. Arandom sample of prices ($) for sleeping bags in this temperaturerange is given below. Assume that the population of xvalues has an approximately normal distribution.

50	90	95	110	85	60	30	23	100	110
105	95	105	60	110	120	95	90	60	70

(a) Use a calculator with mean and sample standard deviationkeys to find the sample mean price x and sample standarddeviation s. (Round your answers to two decimalplaces.)

x =	$
s =	$

(b) Using the given data as representative of the population ofprices of all summer sleeping bags, find a 90% confidence intervalfor the mean price μ of all summer sleeping bags. (Roundyour answers to two decimal places.)

lower limit   Â	$
upper limit   Â	$