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.

1292

1278

1257

1187

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)  
Sample mean =1273.89  

Sample standard deviation =38.49

  

(b)
Sample size =9  
Level of significance=   0.1  
Degree of freedom =   8  
          
t critical value is (by using t table)=1.8595  
          
Confidence interval formula is

=(1250.03,1297.75)          
          
          
          
Lower confidence limit=   1250.03  
          
Upper confidence limit=   1297.75