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Probability

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Probability

by Nidhs » Sun Mar 09, 2008 5:32 pm
Joshua and Jose work att an auto repair center with 4 other workers. For a survey on healthcare insurance, 2 of the 6 workers will be randomly chosen to be interviewd. What is the probability that Joshua and Jose both will be chosen?

1)1/15
2) 1/12
3)1/9
4)1/6
5) 1/3

The correct ans is A and i chose E can someone explain?
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Solution

by Kekela » Mon Mar 10, 2008 6:39 am
1.Probability that Joshua and Jose will be selected is 1/6*1/5
(first Joshua was selected and than Jose)
You must consider the second version when fisrt Jose was selected, therefore 1/6*1/5 should be multiplied by 2.
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by blue_lotus » Mon Mar 10, 2008 7:42 am
P = Number of favourable outcomes/ total outcomes

Total outcome = chosing 2 out of 6 = 6C2 = 15

Chosing 2 out of 2 = 2C2 = 1 . (There is only one way that both Joshua and Jose can be selected)

Therefore P = 1/15


Let me try to explain in another way to

Let Joseua= J, Jose = K others be b,c,d,e
Possible selections are jk,jb,jc,jd,je, kb,kc,kd,ke, bc,bd,be ,cd,ce , de = 15
Favourable outcome of both J and K being selected .Jk are together in the above sequence only once

Therefore P = 1/15
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