stne wrote:
CounterSniper wrote:
Bunuel wrote:
Jessica's laundry basket contains 15 different pairs of socks. If she reaches in to the basket and pulls two socks at random, what is the probability that she pulls out a matching pair?
A. 1/900
B. 1/870
C. 1/210
D. 1/29
E. 1/28
number of ways she can pull two socks of the same colour = 15 ways
no of ways she can pull two socks of any colour = 30c2
probability= 15/30c2 = 15/15*29=1/29
Hi
CounterSniperYou have used two different techniques for solving almost the same question,and arrived at different answers could you care to explain both questions using the same method?
https://gmatclub.com/forum/5-pairs-of-s ... 74309.htmlActually answer should be 2/9 for the question in the link above , but sadly that is not among the options.
Hi
stneconsider below
the first sock can be picked in 30 ways (we have a total of 30 socks)
the second one can be picked in only one way (why ? because we have already picked a sock of a given pair and we have to pick the same one the second time)
p(first sock) = 30/30=1
p(second sock) = 1/29
required probability = 1/29
I have also posted an explanation on the thread you have mentioned above