probability question

5 replies [Last post]
Incognito
Incognito's picture

please solve the following questions

Q1. A box contains 6 red balls, 7 green balls and 5 blue balls. Each ball is of a different size. The probability that the red ball selected is the smallest red ball is:
a. 1/18

b. 1/3

c. 1/6

d. 2/3

 

Q2. There are 50 ten paise coins placed on a table. Six of these shows tails and four shows heads. A coin is chosen at random and fliped(not tossed). This operation is performed seven times. One of these coins is then covered. Of the remaining nine conins, five shows tails and four shows heads. The covered coin shows

a. A head

b. A tail

c. More likely a head

d. More likely a tail

 

rajorshi's picture
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Last seen: 10 years 21 weeks ago
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1. P(a red ball is selected

1. P(a red ball is selected )* P(red is the smallest red ) = 1/18.

or another way : there is only one "smallest red" and selecting that is only one on the first try.

 

poppiyo's picture
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Red Ball

Probability of Red Ball = 6/18 = 1/3

Probability of a small ball = 1/18

Probability of ' Red & small ball' = 1/3 * 1/18 = 1/54

I think am correct.

rajorshi's picture
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NOT in the options

NOT in the options

rajorshi's picture
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Joined: 2007-06-11
probability of a red ball =

probability of a red ball = 6/18
probbility of the sammlest red = 1/6

multiply to get 1/18

Chandan's picture
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Last seen: 11 years 2 weeks ago
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1/54 option is not there but

1/54 option is not there but if u think wisely on d q..then.. it says tht if only 6 red ball of diff sizes wud hav been there then only we can say tat probab is 1/6....but here there r 18 balls of diff sizes..so prob of finding smallest ball is 1/18 i guess...

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