3/29/05 251grass2-051
(Open this document in 'Page Layout' view!) Graded Assignment 2
Name:
Class days and time:
Student number:
Modify the data below as follows: Add the last digit of your student number to 7 in problem 1; Add the
second to last number to the 9 in problem 2.
1) For the following joint probability table (i) check for independence, (ii) Compute E x  and Varx  , (iii)
 
 
Compute Covx, y  or  xy and Corr x, y  or  xy , (iv) Compute Ex  y  and Var x  y  from the
results in (ii) and (iii), (iv) Compute Cov5 x  3, y  and Corr 5x  3, y  using the formulas in section K4 of
251v2out or section C1 of 251var2. Note that y  1y  0 .
x
3
1
.11
5
.08
7
.16
y 3
.10
.14
.10
9
.12
.08
.11
2) For the following sample (i) Compute the sample mean and variance of x , (ii) Compute Covx, y  or
s xy and Corr x, y  or rxy , (iii) Compute the sample mean and variance of x  y  from the results in (i)
and (ii). (iv) Compute Cov5 x  3,2 y  and Corr 5x  3,2 y  using the formulas in section K4 of
251v2out or section C1 of 251var2. Note that 2 y  2 y  0 .
y
x
9
2
4
4
6
2
2
5
1
7
1
6
3
5
10
-3