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6 cards are numbered with 1, 2,3, 4, 5, and 6. Firstly, one [#permalink]

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02 Aug 2006, 20:41

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

6 cards are numbered with 1, 2,3, 4, 5, and 6. Firstly, one cards was picked up and replaced back, then, the second cark was picked up randomly. If the sum of the numbers in the 2 cards is 8, what is the probability that one of the cards has number 5?

Re: question bank probability question [#permalink]

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05 Aug 2006, 20:01

apollo168 wrote:

6 cards are numbered with 1, 2,3, 4, 5, and 6. Firstly, one cards was picked up and replaced back, then, the second cark was picked up randomly. If the sum of the numbers in the 2 cards is 8, what is the probability that one of the cards has number 5?

Prob of picking 2 cards = 6c2 = 15
Prob of favourable events = {(3,5)}

2/5 Total possibilities 4,4 2,6 6,2 3,5 5,3 5 is there in 2 out of total 5.

hi Ps,

Can the question be ineterpreted as follows

5, 3 and 3, 5 are the two options if the sum is the 8

prob = 2/(6x6) =1/18

why do we conclude that the prob is among all combos of 8 as sum ?

thanks

The bold part will be right is asked: what is the prob that sum is 8 AND one of the cards bears a 5.

But question is asking: prob of having one card as 5 when the sum of two cards already drawn is 8.

6 cards are numbered with 1, 2,3, 4, 5, and 6. Firstly, one cards was picked up and replaced back, then, the second cark was picked up randomly. up untill here the question says cards were drawn one after the other . If the sum of the numbers in the 2 cards is 8, (does not say in all such card drawing instances.). what is the probability that one of the cards has number 5?

I see your point but I dont think this problem is worded properly. I hope we do not see such vague questions.