Question

The method of tree ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population of xvalues has an approximately normal distribution.

1229

1215

1215

1320

1268

1316

1275

1317

1275

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

x =	A.D.
s =	yr

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

lower limit	A.D.
upper limit	A.D.

Answer 1

(a)  

Mean	1270
Standard Deviation	42.7347

(b) The critical t-value for ?=0.1 and df = 8 degrees of freedom is tc?=1.86.

The 90% confidence for the population mean ? is computed using the following expression

Therefore, based on the information provided, the 90 % confidence for the population mean ? is

Lower limit	1243.511
Upper limit	1296.489