In: Statistics and Probability
The income of males in each state of the United States, including the District of Columbia and Puerto Rico, are given in table #9.3.3, and the income of females is given in table #9.3.4 ("Median income of," 2013). Is there enough evidence to show that the mean income of males is more than of females? Test at the 1% level.
Table #9.3.3: Data of Income for Males
$42,951 |
$52,379 |
$42,544 |
$37,488 |
$49,281 |
$50,987 |
$60,705 |
$50,411 |
$66,760 |
$40,951 |
$43,902 |
$45,494 |
$41,528 |
$50,746 |
$45,183 |
$43,624 |
$43,993 |
$41,612 |
$46,313 |
$43,944 |
$56,708 |
$60,264 |
$50,053 |
$50,580 |
$40,202 |
$43,146 |
$41,635 |
$42,182 |
$41,803 |
$53,033 |
$60,568 |
$41,037 |
$50,388 |
$41,950 |
$44,660 |
$46,176 |
$41,420 |
$45,976 |
$47,956 |
$22,529 |
$48,842 |
$41,464 |
$40,285 |
$41,309 |
$43,160 |
$47,573 |
$44,057 |
$52,805 |
$53,046 |
$42,125 |
$46,214 |
$51,630 |
Table #9.3.4: Data of Income for Females
$31,862 |
$40,550 |
$36,048 |
$30,752 |
$41,817 |
$40,236 |
$47,476 |
$40,500 |
$60,332 |
$33,823 |
$35,438 |
$37,242 |
$31,238 |
$39,150 |
$34,023 |
$33,745 |
$33,269 |
$32,684 |
$31,844 |
$34,599 |
$48,748 |
$46,185 |
$36,931 |
$40,416 |
$29,548 |
$33,865 |
$31,067 |
$33,424 |
$35,484 |
$41,021 |
$47,155 |
$32,316 |
$42,113 |
$33,459 |
$32,462 |
$35,746 |
$31,274 |
$36,027 |
$37,089 |
$22,117 |
$41,412 |
$31,330 |
$31,329 |
$33,184 |
$35,301 |
$32,843 |
$38,177 |
$40,969 |
$40,993 |
$29,688 |
$35,890 |
$34,381 |
Ho : µ1 - µ2 = 0
Ha : µ1-µ2 > 0
Level of Significance , α =
0.01
Sample #1 ----> male
mean of sample 1, x̅1=
46453.31
standard deviation of sample 1, s1 =
7030.712514
size of sample 1, n1= 52
Sample #2 ----> female
mean of sample 2, x̅2=
36511.000
standard deviation of sample 2, s2 =
6138.12
size of sample 2, n2= 52
difference in sample means = x̅1-x̅2 =
46453.308 - 36511.0000
= 9942.3077
std error , SE = √(s1²/n1+s2²/n2) =
1294.2733
t-statistic = ((x̅1-x̅2)-µd)/SE = (
9942.3077 / 1294.2733 )
= 7.6818
Degree of freedom, = 100
p-value =
0.0000 [excel function: =T.DIST.RT(t stat,df)
]
Conclusion: p-value<α , Reject null
hypothesis
there is enough evidence that mean income of males is
more than of females