Question

The number of robocalls received by a given household in twelve randomly selected weeks results in the following data set: {9, 7, 2, 9, 4, 8, 4, 10, 15, 10, 20, 8}. Use this to find the 90% confidence interval estimate of the mean number of calls received per week. Use a T-interval.

Select one:

a. (5.72, 11.94)

b. (6.06, 11.60)

c. (6.30, 11.37)

d. (6.51, 11.16)

e. (4.44. 13.22)

f. (6.61, 11.06)

Answer 1

c. (6.30, 11.37)

We have for given data,          
              
Sample mean =8.83      
Sample standard deviation =4.896  
Sample size =12      
Level of significance=1-0.90=0.1      
Degree of freedom =11      
              
t critical value is (by using t table)=1.796      
              
Confidence interval formula is               


=(6.30,11.37)