In: Statistics and Probability
.Finance course grade information regarding male and female students of a large university is shown below (?"and ?!unknown) and assumed unequal).
Female |
Male |
|
Sample Size |
24 |
28 |
Sample Mean Grade |
29.8 |
27.3 |
Sample Variance |
6,554 |
3,276 |
Not: You have to draw the table to see which area that you have to calculate
SOLUTION:
a)
Ho : µ1 - µ2 =
0
Ha : µ1-µ2 > 0
Level of Significance , α =
0.05
Sample #1 ----> 1
mean of sample 1, x̅1= 29.80
standard deviation of sample 1, s1 =
80.95677859
size of sample 1, n1= 24
Sample #2 ----> 2
mean of sample 2, x̅2= 27.300
standard deviation of sample 2, s2 =
57.24
size of sample 2, n2= 28
difference in sample means = x̅1-x̅2 =
29.800 - 27.3000 =
2.5000
std error , SE = √(s1²/n1+s2²/n2) =
19.7505
t-statistic = ((x̅1-x̅2)-µd)/SE = ( 2.5000
/ 19.7505 ) = 0.1266
t-critical value , t* =
1.6839 (excel function: =t.inv(α,df)
Decision: | t-stat | < | critical value |, so, Do
not Reject Ho
p-value = 0.44995
[excel function: =T.DIST.RT(t stat,df) ]
Conclusion: p-value>α , Do not reject null
hypothesis
There is no enough evidence to support the claim
b)
Degree of freedom, DF=
40
t-critical value = t α/2 =
1.684 (excel formula =t.inv(α/2,df)
std error , SE = √(s1²/n1+s2²/n2) =
19.751
margin of error, E = t*SE = 1.684
* 19.751 = 33.256946
difference of means = x̅1-x̅2 = 29.8000
- 27.300 = 2.5000
confidence interval is
Interval Lower Limit = (x̅1-x̅2) - E =
2.5000 - 33.257 =
-30.757
Interval Upper Limit = (x̅1-x̅2) + E =
2.5000 - 33.257 =
35.757
(OR) TRY THIS ANSWER
(a)
--------------------------------------
(b)
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