P can hit a target 4 times in 5 shots, Q, 3 times in 4 shots : Quant Question Archive [LOCKED]
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# P can hit a target 4 times in 5 shots, Q, 3 times in 4 shots

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Intern
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P can hit a target 4 times in 5 shots, Q, 3 times in 4 shots [#permalink]

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10 Dec 2003, 05:50
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

P can hit a target 4 times in 5 shots, Q, 3 times in 4 shots and R, twice in 3 shots,. They fire simultaneously. What is the probability that at least 2 shots hit?
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10 Dec 2003, 06:03
5/6 ...i suppose..
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10 Dec 2003, 06:29
at least 2 means that 2 or 3

P(all 3)=4/5*3/4*2/3=2/5
P(2)=[4/5*3/4*1/3]+[3/4*2/3*1/5]+[4/5*2/3*1/4]=1/5+1/10+2/15=13/30

P=2/5+13/30=25/30=5/6
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10 Dec 2003, 07:41
Right.
5/6 it is...
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10 Dec 2003, 13:48
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13 Dec 2003, 00:27
4128851 wrote:
P can hit a target 4 times in 5 shots, Q, 3 times in 4 shots and R, twice in 3 shots,. They fire simultaneously. What is the probability that at least 2 shots hit?

prob of hitting zero shots = 1/5 * 1/4 *1/3 = 1/60

prob of hitting exactly one shot = 4/5 * 1/4*1/3 + 1/5* 3/4 * 2/3 + 1/5 * 1/4 * 2/3 = 9/60

P(0) + P(1) = 1/60 + 9/60 = 10/60 =1/6

required prob = 1- 1/6 = 5/6
Re: probability!!   [#permalink] 13 Dec 2003, 00:27
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