Question
In: Statistics and Probability
Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval...
Refer to Exhibit 8-1. If the sample mean is 9 hours, then the 95% confidence interval is approximately
Exhibit 8-1: In order to estimate the average time spent on the computer terminals per student at a local university, data were collected from a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.2 hours.
a. 7.04 to 110.96 hours
b. 7.36 to 10.64 hours
c. 7.80 to 10.20 hours
d. 8.74 to 9.26 hours
Solutions
Expert Solution
Solution :
Given that,
Point estimate = sample mean = 
= 9
Population standard deviation = 
=1.2
Sample size n =81
At 95% confidence level the z is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
Z/2
= Z0.025 = 1.96 ( Using z table )
Margin of error = E = Z/2
* ( 
/
= 1.96 * ( 1.2 /
= 0.26
At 95% confidence interval estimate of the population mean
is,
- E < 
<
+ E
9 - 0.26 <
< 9+ 0.26
8.74 <
< 9.26
d. 8.74 to 9.26 hours
orchestra answered 2 years agoRelated Solutions
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