Problems, Chapter 8
8
a)
y has units of seconds, x has units of feet
b)
the slope has units of seconds/ft
c)
The slope is positive, as the height increases, so does the length of the ride
11
a)
the correlation coefficient is r = .845
b)
The price will be .845 standard deviations above the mean price
c)
The price of the home should be 1.69 standard deviations below the mean price
12
I did this by mistake.
Since it was done, I left it in.
a)
b)
The ride length would be .352 standard deviations below the mean
c)
The ride length would be 1.06 standard deviations above the mean
15
a)
Probably.
The points fall near the line and there is no clear
trend in the residuals.
b)
Therefore, tar accounts for 92.4% of the nicotine variability.
28
SAT  x
GPA  y
mean
1222
2066
r = .47
st dev
83
0.56
a)
0
1.298
b)
It doesn't really indicate anything except that people who score
too low on the exam should not attempt college.
The function
of the y intercept is to adjust the height of the line for the
region in which the line means something.
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 Spring '08
 Weaver
 Math, Statistics, Correlation, Correlation Coefficient, Regression Analysis, Standard Deviation, 1920, 1916, 1918, 1912

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