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STAT 200 Week 7 Homework Problems
10.1.2
Table #10.1.6 contains the value of the house and the amount of rental income in a year that the house brings in ("Capital and rental," 2013). Create a scatter plot and find a regression equation between house value and rental income. Then use the regression equation to find the rental income a house worth $230,000 and for a house worth $400,000. Which rental income that you calculated do you think is closer to the true rental income? Why?
Table #10.1.6: Data of House Value versus Rental
|
Value |
Rental |
Value |
Rental |
Value |
Rental |
Value |
Rental |
|
81000 |
6656 |
77000 |
4576 |
75000 |
7280 |
67500 |
6864 |
|
95000 |
7904 |
94000 |
8736 |
90000 |
6240 |
85000 |
7072 |
|
121000 |
12064 |
115000 |
7904 |
110000 |
7072 |
104000 |
7904 |
|
135000 |
8320 |
130000 |
9776 |
126000 |
6240 |
125000 |
7904 |
|
145000 |
8320 |
140000 |
9568 |
140000 |
9152 |
135000 |
7488 |
|
165000 |
13312 |
165000 |
8528 |
155000 |
7488 |
148000 |
8320 |
|
178000 |
11856 |
174000 |
10400 |
170000 |
9568 |
170000 |
12688 |
|
200000 |
12272 |
200000 |
10608 |
194000 |
11232 |
190000 |
8320 |
|
214000 |
8528 |
208000 |
10400 |
200000 |
10400 |
200000 |
8320 |
|
240000 |
10192 |
240000 |
12064 |
240000 |
11648 |
225000 |
12480 |
|
289000 |
11648 |
270000 |
12896 |
262000 |
10192 |
244500 |
11232 |
|
325000 |
12480 |
310000 |
12480 |
303000 |
12272 |
300000 |
12480 |
|
Value |
Rental |
(x-sample mean of x)^2 |
(y-sample mean of y)^2 |
(x-sample mean of x)(y-sample mean of y) |
|
174375 |
9611.333 |
2.26936E+11 |
230247402.7 |
5527756000 |
|
Mean x |
Mean y |
SSx |
SSy |
SSxy |
Slope = b = SSxy/SSx = 5527756000/2.26936E+11 = 0.024
y-intercept = a = -bx = 9611.333-0.024(174375) = 5426.333
Regression equation: y-intercept = 5426.333+0.024x
House value at $230,000 = 5426.333+0.024(230000) = $10,946.333
House value at $400,000 = 5426.333+0.024(400000) = $15,026.333
Rental income of $10,946.333 for a house valued at $230K is closer to the true rental income because the values fall within the range of the original values.
10.1.4
The World Bank collected data on the percentage of GDP that a country spends on health expenditures ("Health expenditure," 2013) and also the percentage of women receiving prenatal care ("Pregnant woman receiving," 2013). The data for the countries where this information are available for the year 2011 is in table #10.1.8. Create a scatter plot of the data and find a regression equation between percentage spent on health expenditure and the percentage of women receiving prenatal care. Then use the regression equation to find the percent of women receiving prenatal care for a country that spends 5.0% of GDP on health expenditure and for a country that spends 12.0% of GDP. Which prenatal care percentage that you calculated do you think is closer to the true percentage? Why?
Table #10.1.8: Data of Health Expenditure versus Prenatal Care
|
Health Expenditure (% of GDP) |
Prenatal Care (%) |
|
9.6 |
47.9 |
|
3.7 |
54.6 |
|
5.2 |
93.7 |
|
5.2 |
84.7 |
|
10.0 |
100.0 |
|
4.7 |
42.5 |
|
4.8 |
96.4 |
|
6.0 |
77.1 |
|
5.4 |
58.3 |
|
4.8 |
95.4 |
|
4.1 |
78.0 |
|
6.0 |
93.3 |
|
9.5 |
93.3 |
|
6.8 |
93.7 |
|
6.1 |
89.8 |
|
Health Expenditure (% of GDP) |
Prenatal Care (%) |
(x-mean)^2 |
(y-mean)^2 |
(x-mean x)(y-mean y) |
|
6.126667 |
79.91333 |
56.72933 |
5318.417 |
94.20466667 |
|
mean |
mean |
SSx |
Ssy |
Ssxy |
Slope = b = SSxy/SSx = 94.205/56.729 = 1.66
y-intercept = a = y ̅-bx = 79.913-1.661(6.127) = 69.74%
Regression equation: y-intercept = 69.74+1.66x
prenatal care for a country that spends 5.0% of GDP = 69.74+1.66(5) = 78.04%
prenatal care for a country that spends 12.0% of GDP = 69.74+1.66(12) = 89.66%
The prenatal care for a country that spends 5% of GDP is closer to the true percentage because it is closer to the regression line
10.2.2
Table #10.1.6 contains the value of the house and the amount of rental income in a year that the house brings in ("Capital and rental," 2013). Find the correlation coefficient and coefficient of determination and then interpret both.
Table #10.1.6: Data of House Value versus Rental
|
Value |
Rental |
Value |
Rental |
Value |
Rental |
Value |
Rental |
|
81000 |
6656 |
77000 |
4576 |
75000 |
7280 |
67500 |
6864 |
|
95000 |
7904 |
94000 |
8736 |
90000 |
6240 |
85000 |
7072 |
|
121000 |
12064 |
115000 |
7904 |
110000 |
7072 |
104000 |
7904 |
|
135000 |
8320 |
130000 |
9776 |
126000 |
6240 |
125000 |
7904 |
|
145000 |
8320 |
140000 |
9568 |
140000 |
9152 |
135000 |
7488 |
|
165000 |
13312 |
165000 |
8528 |
155000 |
7488 |
148000 |
8320 |
|
178000 |
11856 |
174000 |
10400 |
170000 |
9568 |
170000 |
12688 |
|
200000 |
12272 |
200000 |
10608 |
194000 |
11232 |
190000 |
8320 |
|
214000 |
8528 |
208000 |
10400 |
200000 |
10400 |
200000 |
8320 |
|
240000 |
10192 |
240000 |
12064 |
240000 |
11648 |
225000 |
12480 |
|
289000 |
11648 |
270000 |
12896 |
262000 |
10192 |
244500 |
11232 |
|
325000 |
12480 |
310000 |
12480 |
303000 |
12272 |
300000 |
12480 |
Correlation coefficient: r = SSxy/√SSxSSy = 5527756000/√2.26936E+11*230247402.7 = 0.7647
0.7647 is close to 1, therefore there is a strong, positive correlation
Coefficient of determination: r^2 = (r)^2 = (0.7647)^2 = 0.5848
Thus, 58.48% of the variation in rental is explained to the linear relationship between house value versus rental. The other 41.52% of the variation is due to other factors.
10.2.4
The World Bank collected data on the percentage of GDP that a country spends on health expenditures ("Health expenditure," 2013) and also the percentage of women receiving prenatal care ("Pregnant woman receiving," 2013). The data for the countries where this information is available for the year 2011 are in table #10.1.8. Find the correlation coefficient and coefficient of determination and then interpret both.
Table #10.1.8: Data of Health Expenditure versus Prenatal Care
|
Health Expenditure (% of GDP) |
Prenatal Care (%) |
|
9.6 |
47.9 |
|
3.7 |
54.6 |
|
5.2 |
93.7 |
|
5.2 |
84.7 |
|
10.0 |
100.0 |
|
4.7 |
42.5 |
|
4.8 |
96.4 |
|
6.0 |
77.1 |
|
5.4 |
58.3 |
|
4.8 |
95.4 |
|
4.1 |
78.0 |
|
6.0 |
93.3 |
|
9.5 |
93.3 |
|
6.8 |
93.7 |
|
6.1 |
89.8 |
Correlation coefficient: r = SSxy/√SSxSSy = 94.20466667/√56.72933*5318.417 = 0.1715
0.1715 is closer to 0, therefore there is a weak correlation
Coefficient of determination: r^2 = (r)^2 = (0.1715)^2 = 0.0294
Thus, 2.94% of the variation in prenatal care is explained to the weak linear relationship between house value versus rental. The other 97.06% of the variation is due to other factors.
10.3.2
Table #10.1.6 contains the value of the house and the amount of rental income in a year that the house brings in ("Capital and rental," 2013).
Test at the 5% level for a positive correlation between house value and rental amount.
Table #10.1.6: Data of House Value versus Rental
|
Value |
Rental |
Value |
Rental |
Value |
Rental |
Value |
Rental |
|
81000 |
6656 |
77000 |
4576 |
75000 |
7280 |
67500 |
6864 |
|
95000 |
7904 |
94000 |
8736 |
90000 |
6240 |
85000 |
7072 |
|
121000 |
12064 |
115000 |
7904 |
110000 |
7072 |
104000 |
7904 |
|
135000 |
8320 |
130000 |
9776 |
126000 |
6240 |
125000 |
7904 |
|
145000 |
8320 |
140000 |
9568 |
140000 |
9152 |
135000 |
7488 |
|
165000 |
13312 |
165000 |
8528 |
155000 |
7488 |
148000 |
8320 |
|
178000 |
11856 |
174000 |
10400 |
170000 |
9568 |
170000 |
12688 |
|
200000 |
12272 |
200000 |
10608 |
194000 |
11232 |
190000 |
8320 |
|
214000 |
8528 |
208000 |
10400 |
200000 |
10400 |
200000 |
8320 |
|
240000 |
10192 |
240000 |
12064 |
240000 |
11648 |
225000 |
12480 |
|
289000 |
11648 |
270000 |
12896 |
262000 |
10192 |
244500 |
11232 |
|
325000 |
12480 |
310000 |
12480 |
303000 |
12272 |
300000 |
12480 |
Ho:ρ=0(There is no correlation)
HA:ρ≠0(There is a correlation)
or HA:ρ<0(There is a negative correlation)
or HA:ρ>0(There is a positive correlation)
α level = 0.05
10.3.4
The World Bank collected data on the percentage of GDP that a country spends on health expenditures ("Health expenditure," 2013) and also the percentage of women receiving prenatal care ("Pregnant woman receiving," 2013). The data for the countries where this information is available for the year 2011 are in table #10.1.8.
Test at the 5% level for a correlation between percentage spent on health expenditure and the percentage of women receiving prenatal care.
Table #10.1.8: Data of Health Expenditure versus Prenatal Care
|
Health Expenditure (% of GDP) |
Prenatal Care (%) |
|
9.6 |
47.9 |
|
3.7 |
54.6 |
|
5.2 |
93.7 |
|
5.2 |
84.7 |
|
10.0 |
100.0 |
|
4.7 |
42.5 |
|
4.8 |
96.4 |
|
6.0 |
77.1 |
|
5.4 |
58.3 |
|
4.8 |
95.4 |
|
4.1 |
78.0 |
|
6.0 |
93.3 |
|
9.5 |
93.3 |
|
6.8 |
93.7 |
|
6.1 |
89.8 |
11.1.2
Researchers watched groups of dolphins off the coast of Ireland in 1998 to determine what activities the dolphins partake in at certain times of the day ("Activities of dolphin," 2013). The numbers in table #11.1.6 represent the number of groups of dolphins that were partaking in an activity at certain times of days. Is there enough evidence to show that the activity and the time period are independent for dolphins? Test at the 1% level.
Table #11.1.6: Dolphin Activity
|
Activity |
Period |
Row Total |
|||
|
|
Morning |
Noon |
Afternoon |
Evening |
|
|
Travel |
6 |
6 |
14 |
13 |
39 |
|
Feed |
28 |
4 |
0 |
56 |
88 |
|
Social |
38 |
5 |
9 |
10 |
62 |
|
Column Total |
72 |
15 |
23 |
79 |
189 |
11.1.4
A person’s educational attainment and age group was collected by the U.S. Census Bureau in 1984 to see if age group and educational attainment are related. The counts in thousands are in table #11.1.8 ("Education by age," 2013). Do the data show that educational attainment and age are independent? Test at the 5% level.
Table #11.1.8: Educational Attainment and Age Group
|
Education |
Age Group |
Row Total |
||||
|
|
25-34 |
35-44 |
45-54 |
55-64 |
>64 |
|
|
Did not complete HS |
5416 |
5030 |
5777 |
7606 |
13746 |
37575 |
|
Competed HS |
16431 |
1855 |
9435 |
8795 |
7558 |
44074 |
|
College 1-3 years |
8555 |
5576 |
3124 |
2524 |
2503 |
22282 |
|
College 4 or more years |
9771 |
7596 |
3904 |
3109 |
2483 |
26863 |
|
Column Total |
40173 |
20057 |
22240 |
22034 |
26290 |
130794 |
11.2.4
In Africa in 2011, the number of deaths of a female from cardiovascular disease for different age groups are in table #11.2.6 ("Global health observatory," 2013). In addition, the proportion of deaths of females from all causes for the same age groups are also in table #11.2.6. Do the data show that the death from cardiovascular disease are in the same proportion as all deaths for the different age groups? Test at the 5% level.
Table #11.2.6: Deaths of Females for Different Age Groups
|
Age |
5-14 |
15-29 |
30-49 |
50-69 |
Total |
|
Cardiovascular Frequency |
8 |
16 |
56 |
433 |
513 |
|
All Cause Proportion |
0.10 |
0.12 |
0.26 |
0.52 |
|
11.2.6
A project conducted by the Australian Federal Office of Road Safety asked people many questions about their cars. One question was the reason that a person chooses a given car, and that data is in table #11.2.8 ("Car preferences," 2013).
Table #11.2.8: Reason for Choosing a Car
|
Reliability |
Cost |
Performance |
Comfort |
Looks |
|
|
84 |
62 |
46 |
34 |
47 |
27 |
Do the data show that the frequencies observed substantiate the claim that the reasons for choosing a car are equally likely? Test at the 5% level.
Ho: the reason for choosing a car is equally likely
Ha: the reason for choosing a car is not equally likely
Observed frequency = 84+62+46+34+47+27 = 300
Expected value = sum of all frequency/#rows = 300/6 = 50
Percentage of GDP a country spends
9.6 3.7 5.2 5.2 10 4.7 4.8 6 5.4 4.8 4.0999999999999996 6 9.5 6.8 6.1 47.9 54.6 93.7 84.7 100 42.5 96.4 77.099999999999994 58.3 95.4 78 93.3 93.3 93.7 89.8
Health Expenditure %
Pre-natal Care %