Question

The method of tree-ring dating gave the following years A.D. for an archaeological excavation site. Assume that the population of x values has an approximately normal distribution. 1,285 1,194 1,299 1,180 1,268 1,316 1,275 1,317 1,275 (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 = 1268 Correct: Y

our answer is correct. A.D. s = 43 Incorrect: Your answer is incorrect. yr

(b) When finding an 90% confidence interval, what is the critical value for confidence level? (Give your answer to three decimal places.) tc = 1.860 Correct: Your answer is correct.

What is the maximal margin of error when finding a 90% confidence interval for the mean of all tree-ring dates from this archaeological site? (Round your answer to the nearest whole number.) E = :

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 Incorrect: . A.D. upper limit Incorrect:

Answer 1

a. Sample mean is

Create the following table.

data	data-mean	(data - mean)2
1285	17.3333	300.44328889
1194	-73.6667	5426.78268889
1299	31.3333	981.77568889
1180	-87.6667	7685.45028889
1268	0.33330000000001	0.11108889000001
1316	48.3333	2336.10788889
1275	7.3333	53.77728889
1317	49.3333	2433.77448889
1275	7.3333	53.77728889

Find the sum of numbers in the last column to get.

Hence standard deviation is

b. t value is given as tc = 1.860

So Margin of Error is

Hence CI is

Lower limit is 1238

Upper limit is 1298