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Math 147 - Fall 1997 - Test # 2

Answer Key

1. (a) is False, (b) is True, (c) is True, (d) is False. Answer: (e)
2. (a) is True, (b) is False, (c) is True. Answer: (e)
3. (a) is True, (b) is False, (c) is False, (d) is False. Answer: (a)
4. (I) is False, (II) is False, (III) is False, (IV) is False. Answer: (e)
5. (a) is True, (b) is True, (c) is True. Answer: (e)
6. (a) is True, (b) is True, (c) is True. Answer: (e)
7. (a) is True, (b) is False, (c) is False. Answer: (a)
8. (a) is False, (b) is False, (c) is True. Answer: (c)

9. The above figure is a scatter diagram of two variables. The solid line represents the SD line,

while the dashed line represents the regression line. The SD of Y is about 2.8 while the

SD of X is about 5.6. Looking at the figure, we can see that the correlation coefficient for this

set of data is about 0.75. If we observe an x-value of 30, our prediction of the

y-value is 15.6. The R.M.S. error of this scatter diagram is about 1.8. The point ( 31, 18 )

is on the scatter diagram, and the residual for this point is about 2.0.

10.

x	y	x in standard units	y in standard units	product
1	1	-1.34	-1.48	1.98
2	3	-0.80	-0.80	0.64
3		-0.27	-0.12	0.32
4	4	0.27	0.56	0.15
5	4	0.80	0.56	0.45
	5	1.34	1.24	1.66

r = .877.

11.

a) (y - 40)/10 = (-.6)(x - 180)/24 or y = -x/4 + 85.

b) 37 minutes

c) 8.00

d) 6.68%

e) 15.87%

f) 40 minutes

g) False, because 340 pounds is too far out of the range of the data gathered to trust this inference.

12.

a) 2/3

b) 1/7

c) 33/100

d) 1/2

e) No

f) Yes

g) No

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