Tricky S1 help (Probability) Watch

Mister Master
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#1
Report Thread starter 8 years ago
#1
hi,

I was wondering if anyone could help me on
Q 1 b)

and Q 6 (b)

For Q(1 .b the fist colum i.e where no dogs , I think it should have been P(X=0)=3/7 , but the answer is apparently 1/7

and Q 6b . I cant really show it ..
Can someone offer any help?

Thanks
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Weeman5872
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Report 8 years ago
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For 1b, use a probability tree

The reason its \frac{1}{7} is because, for no dogs to be picked, two cats must be picked.

So: P(X = 0) = \frac{3}{7} \times \frac{2}{6} = \frac{6}{42} = \frac{1}{7}
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Mister Master
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Thanks "Weeman" , does anyone have any idea on the last Q 6 b..I will be grateful
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Mister Master
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Can noone help :sad: ?
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mjtriggs
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Just checking that I'm on the right lines, did you get 7/30 for 6a?
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mjtriggs
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Okay, sorry about the double post, think I have the answer.

The probability of a card A1 being chosen from pack A is 5/30. Or 1/6.

This card is then placed into pack B.

The probability of then choosing a card with the first digit "1" from B is 8/32, or 1/4.

Therefore, the probability of choosing a card with the first digit of "1" from both decks is 1/4 * 1/6 = 1/24.
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