Book Problem Set #6
Round all of your final answers to four decimal places if necessary.
#1) A sample survey contacted an SRS of 663 registered voters in Oregon shortly after an
election and asked respondents whether they had voted.
Suppose that p=0.56 (56% of
registered voters actually voted).
We will see in the next chapter that
p
ˆ
~ N(0.56, 0.019).
a) What is the probability that the survey result will be within 4 percentage points of the
truth about the population?
b) What is the probability that the survey result will differ from the truth about the
population by more than 2 percentage points?
#2) Melissa has invested 40% of her funds in Tbills and 60% of her funds in stocks.
If X
is the annual return on Tbills and Y the annual return on stocks, the portfolio rate of
return is:
R= 0.4X + 0.6Y
The returns X and Y are random variables because they vary from year to year:
X= annual return on Tbills
μ
X
= 6
σ
X
= 4.2
Y= annual return on stocks
μ
Y
= 14
σ
Y
= 15
correlation between X and Y
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 '08
 ABDUS,S.
 annual return, Advisory Board, X= annual return, Y= annual return

Click to edit the document details