Question
In: Statistics and Probability
A university surveyed recent graduates of the English department for their starting salaries. Three hundred graduates...
A university surveyed recent graduates of the English department for their starting salaries. Three hundred graduates returned the survey. The average salary was $25,000. The sample standard deviation was $1,500. What is the 95% confidence interval for the mean salary of all graduates from the English department?
Solutions
Expert Solution
Solution :
Given that,
= $25000
s =$1500
n =300
Degrees of freedom = df = n - 1 = 300- 1 = 299
a ) At 95% confidence level the t is ,
= 1 - 95% = 1 - 0.95 = 0.05
/
2= 0.05 / 2 = 0.025
t
/2,df = t0.025,299 = 1.968 ( using student t
table)
Margin of error = E = t/2,df
* (s /
= 1.968 * (1500 /
= 170.4338
The 95% confidence interval estimate of the population mean is,
- E < 
<
+ E
25000- 170.4338 <
< 25000+ 170.4338
24829.5662 <
< 25170.4338
( 24829.5662 ,25170.4338)
orchestra answered 2 years agoRelated Solutions
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