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PS: Prob

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PS: Prob

by OSHO » Wed Aug 08, 2007 9:18 am
Out of 100 lottery tickets, each having 50% chance of winning, 2 tickets are bought at random. What is the probability that at least one ticket will win?
(A) 1/4
(B) 1/2
(C) 49/198
(D) 149/198
(E) 3/4
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by beny » Wed Aug 08, 2007 5:37 pm
This question is stupid. Don't worry about it.

(The OA assumes that 50% of the tickets are winning tickets and 50% are losing tickets, not that each ticket has a 50% chance of winning.)
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by gabriel » Thu Aug 09, 2007 12:35 am
beny wrote:This question is stupid. Don't worry about it.

(The OA assumes that 50% of the tickets are winning tickets and 50% are losing tickets, not that each ticket has a 50% chance of winning.)
yeah .. was puzzled about how out of 100 tickets each has a 50% chance of winning ..
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E?

by g2000 » Thu Aug 09, 2007 9:15 am
My reasoning is as follows:

If each ticket has 50% chance of win, then
the probability the first one wins is 50% and so its the second one.

The probability that no one wins is as follows:
first one does not win AND second one does not win

1/2 * 1/2
= 1/4

And the probability that at least one wins is
1 - (both not wins)
1 - 1/4
3/4 <-- my answer
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