Trick Probability question

[ssky]

An eight-card deck consists of 4 pairs of each suit. 2 cards are taken at random without repetition. What is the probability to have two cards of the same suit?

A. 1/2
B.1/3
C.1/4
D.1/7
E.1/8

[Meggieski]

Not sure if I am right..

Total possible combinations of two cards is 8*7/2*1 (because order doesnt matter) gives 28 combinations.

Four of those are matches. So the prob is 4/28 or 1/7. D

OA?

[saketbansal]

D, as it has 4 pairs

2/8* 1/7 * 4(for all pairs) = 1/7

[NishantG]

Answer is D for me

Picking up first card as I one can pick any card is 1
Picking 2nd card is 1/7

Probability = 1/7

[ramiy]

ans is D

As n(s) = 8C2 = 28 Selecting two out of 8 cards present
n(E) = ( 2C2+2C2+2C2+2C2) = 4 .. This is probabiltiy of getting two cards of same suit .

Now P(s) = N(e)/n(s) = 4/28 = 1/7

Thanks

[kiranlegend]

Originally Posted by ssky

An eight-card deck consists of 4 pairs of each suit. 2 cards are taken at random without repetition. What is the probability to have two cards of the same suit?

A. 1/2
B.1/3
C.1/4
D.1/7
E.1/8

8 C 2 = 28

one card is drawn from one suit among 4 suits available = 4 c 1 = 4

2nd card should be from that suit only = 1c1

so the ans = 1/7

what is OA?

[ssky]

OA is D.. good job guys. You all will get good scores in GMAt..Keep up the good work.

[Meggieski]

Don't speak too soon! I thought this problem was easy and got a 550! But I will hope you are right for my second pass at it