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probability medium (550-600)

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probability medium (550-600)

by Night reader » Thu Dec 02, 2010 11:34 am
One bag contains 100 marbles, numbered consecutively from 0 to 99, inclusive. Another bag contains 60 marbles, numbered consecutively from 90 to 149, inclusive. If a marble is randomly drawn from each bag, what is the probability that the two marbles have the same number?

(A) 1/10
(B) 1/60
(C) 1/100
(D) 1/600
(E) 1/6000
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by oddball » Thu Dec 02, 2010 12:16 pm
Total number of possible selection = 60*100 = 6000

Number of selection with same number = 10

Probability = 10/6000 = 1/600

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by shovan85 » Thu Dec 02, 2010 12:18 pm
Night reader wrote:One bag contains 100 marbles, numbered consecutively from 0 to 99, inclusive. Another bag contains 60 marbles, numbered consecutively from 90 to 149, inclusive. If a marble is randomly drawn from each bag, what is the probability that the two marbles have the same number?

(A) 1/10
(B) 1/60
(C) 1/100
(D) 1/600
(E) 1/6000
Overlapping numbers 90-99 = 10 possibilities.

P(1st pick from 1st bag to get) = 10/100 = 1/10
P(1st pick from 1st bag to get the exact from the first bag) = 1/60

Thus 1/10 * 1/60 = 1/600

IMO D
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