Page 1 of 3
ECO220Y: Homework, Lectures 11 & 12
Readings:
Sections 7.1 – 7.2
Exercises:
7.2, 7.4, 7.5, 7.8, 7.16 – 7.18, 7.32 – 7.34, 7.36, 7.40 – 7.42, 7.47 – 7.50, 7.52, 7.54, 7.56, 7.58,
7.59
Problems:
(1)
Suppose you calculate
x
= $36,
y
= $60, s
X
= $12, s
Y
= $15, and s
XY
= 90. In the data x and y are
measured in Canadian dollars.
After you’ve done this analysis your boss informs you that she wanted these
statistics in U.S. dollars and she wanted to know the variability of the difference between x and y (also in U.S.
dollars).
Revise the original statistics and provide the additional statistic. Show your work.
(2)
Create a new variable Z that is the variable X standardized to have mean 0 and variance 1. (Round to the
first decimal place.) Show your work.
For Questions
(3) – (4)
:
Consider the following four boxes full of balls.
(3)
Suppose you randomly take one ball from box 1, one ball from box 2, one ball from box 3, and one ball from
box 4 and then calculate the mean of the numbers shown on the four balls. Define the random variable X to be
the mean.
What is the probability distribution of X?
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '11
 tanaka
 Standard Deviation, Linear combination

Click to edit the document details