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STAT 230
Extra Problems
1.
QuickWin
lottery tickets cost $1.00 apiece and pay of instantly (in the amount oF $5.00) when
the ticket is a winner. The makers oF
QuickWin
tickets claim that 1 in 10 tickets are winners.
(a) Suppose you buy
QuickWin
tickets until you obtain 2 winners. Let
W
= your net winnings.
±ind
E
(
W
) and Var(
W
) iF the probability
p
oF a winner is
p
=0
.
1 (as claimed by the makers).
(b) Suppose you plan to visit 15 diﬀerent retail outlets and, at each outlet, buy
QuickWin
tickets until you obtain 2 winners. Write down an expression For the probability that, at exactly 3
outlets, 14 or Fewer tickets will be required to obtain 2 winners, while exactly 2 outlets will require
(eek!) 30 or more tickets to produce 2 winners.
(c) Suppose the actual numerical results oF your experiment in visiting the 15 retail outlets
produces the Following Frequency table:
no. oF tickets required

Fewer than 12

12–15

16–19

20–23

24–27

more than 27
Frequency (no. oF outlets)

0
3354
0
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This note was uploaded on 10/21/2010 for the course STAT 230 taught by Professor Various during the Fall '06 term at Waterloo.
 Fall '06
 various

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