1.
(a) Height = 5 percent/$100
(b) Approcximately 30 percent
2.
(a) 1/2, 16%
(b) 8/26 = 0.31, 2/26 = 0.08
(c) long right tail. The mean is higher than the median.
3.
(a) No. Take the example of points earned on a test and points
lost. These are both positive (50,0) (25,25) (40,10) and the
correlation is -1.
(b) Yes, because 68% is within 1 SD of the average. Since
75% is within 1.15 of the averag, then we would estimate the
SD to be 10/1.15= 8.7.
(c) The young group had nearly twice as many men, and so it
is more likely that an outlier (extreme value) is observed.
(d) The average is 3, so the answer is 0
(e) 62
4
(a) Regression estimate is 14.4. The residual SD is 2.4.
We estimate that 40 percent would have more than 15 pounds
of fat.
(b) No, because the averages and SD and correlations for females
could be very different than for males.
5.
(a) No, the studnets would know which size class they were in.
(b) Yes, the students were assigned at random to classes.
(c) Score on standardized tests
(d) Because teachers who self select to teach in the smaller
classes may be different from those who choose not to participate
or who choose the largere classes. For example, they may be
invested in the change occuring and so work extra hard during the
trial period, and their students scores would reflect the extra
effort that they made.
(e) Option 2.