Question

The Wind Mountain archaeological site is located in southwestern New Mexico. Wind Mountain was home to an ancient culture of prehistoric Native Americans called Anasazi. A random sample of excavations at Wind Mountain gave the following depths (in centimeters) from present-day surface grade to the location of significant archaeological artifacts†.

85	45	120	80	75	55	65	60
65	95	90	70	75	65	68

(a) Use a calculator with mean and sample standard deviation keys to find the sample mean x and sample standard deviation s. (Round your answers to one decimal place.)

x =	cm
s =	cm

(b) Compute a 99% confidence interval for the mean depth μ at which archaeological artifacts from the Wind Mountain excavation site can be found. (Round your answers to one decimal place.)

lower limit	cm
upper limit	cm

Answer 1

a)

From given sample ,

= X / n = 74.2

S = sqrt( X² - n² / n-1) = 18.3

b)

t critical value at 0.01 level with 14 df = 2.977

99% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

74.2 - 2.977 * 18.3 / sqr(15) < < 74.2 + 2.977 * 18.3 / sqrt(15)

60.1 < < 88.3

Lower limit = 60.1

Upper limit = 88.3