Magenta96
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#1
Report Thread starter 6 years ago
#1
Kevin hosts a TV programme about star signs. There are 12 star signs in total. He picks people at random and asks them what sign they were born under. What is the probability that at least 2 out 5 people have the same star sign?

I don't know how to this question but I tried this way:

P(2 people have same star sign and 3 people have different)
= (1/12 * 1/12 * 11/12 * 10/12 * 9/12)  +

P(3 people have same star sign and 2 people have different)
= (1/12 * 1/12 * 1/12 * 11/12 * 10/12) +

P(4 people have same star sign and 1 person is different)
= (1/12 * 1/12 * 1/12 * 1/12 * 11/12) +

P(all 5 have same star sign)
= (1/12)^5

= 0.00447, the markscheme says it's 0.618, how?
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lilmisssunshine13
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#2
Report 6 years ago
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i feel your pain, i did S1 last year and this question really stumped me.

because i did it so long ago, i couldn't at first remember how to do it - but this thread should help:

http://www.thestudentroom.co.uk/show....php?t=1913648

don't worry, there was never a question like that on my actual S1 exam!
good luck
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