Sample_Midterm1 - Stat 155.8 Midterm 1 Wednesday...

Stat 155.8 Midterm 1
Wednesday, February 16, 2005
Name (please print):
INSTRUCTIONS:
1. Answer all questions and show all work on the exam in the
space provided. Please be free to use the back pages if
necessary. You will not receive credit if you do not justify
your answers.
2. Circle your final answers.
3. Remember to sign the Honor Pledge below.
I pledge that I have neither given nor received unauthorized assistance
during this examination.
Signed: ----------------------------------------------------------------------

1. (8 points) Suppose we are interested in the relationship between height and
weight. To examine this relationship, we take a sample of 100 people and measure both
the height and weight of each (I.e. for each person, we end up with a pair of numbers (x,
y), where x is the height in inches and y is the weight in kilograms .). For this
relationship, write down the units of:
a) the correlation r between height and weight.
b) a and b where
bx a y + =
ˆ
is the regression line of weight on height.
c)
X
, the mean height.
d) S
x
2
, the variance of the variable height.
2. (13 points) The following is the stemplot of the salaries (in thousand of dollars) of
15 employees in a company.
8
7
6
5
4
3
2
1
3
1
2
6
1
4
1
7
2
3
8
9
3
5
8
a) Find the five number summary of the distribution.
b) Find the mean of the distribution.

c) Is the distribution symmetric/skewed left/skewed right?