Latest TCS Aptitude Question SOLUTION: A drawer has 4 red hats and 4 blue hats. Find the probability of getting exactly 3 red hats or exactly 3 blue hats when taking out 4 hats randomly out of the drawer and immediately

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(#M40024421) TCS question Keep an EYE

A drawer has 4 red hats and 4 blue hats. Find the probability of getting exactly 3 red hats or exactly 3 blue hats when taking out 4 hats randomly out of the drawer and immediately returning every hat to the drawer before taking out the next?
option
a)1/2
b)1/4
c)1/8
d)none of these

Asked In TCS Karthika (10 years ago)

Unsolved Read Solution (7)

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sandy  (10 years ago)

i think ans is 1/8
selecting a red hat can be done in 4c1/8c1 ways=1/2
it is asked that 3 red or 3 blue (rrrb)or (bbbr)
(1/2.1/2.1/2.1/2)+(1/2.1/2.1/2.1/2)=1/16+1/16=1/8

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sandeep  (10 years ago)

Probablity of taking out a particular color hat = 4/8 = 1/2

P(BBBR) = (1/2)^4
P(BBRB) = (1/2)^4
P(BRBB) = (1/2)^4
P(RBBB) = (1/2)^4
total = 4 * (1/2)^4

similary for (RRRB) = 4 * (1/2)4

answer = 8 * (1/2) ^4 = 1/2

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Dipika Jha  (10 years ago)

ans is 1/2 bcz there are total of 8 cases of getting exactly 3 red or exactly 3 blue so we will have 8*(4/8)*(4/8)*(4/8)*(4/8)=1/2

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Alok kumar  (10 years ago)

2*(4/8*4/8*4/8*4/8)=1/8

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Sindhusha Thota  (10 years ago)

4c3*4c1*2/4^4=1/8

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Guru Pranav  (10 years ago)

ans is 1/8

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