A pair of fair dice is tossed. Given that the sum is 6, find the probability that one of the dice shows 2. (Hint: Possible pairs to achieve a 6, (1, 5), (2, 4), …)

Question

anonymous · Answer

2/5

anonymous · Answer

may i know how did you get the answe ? thank you !

anonymous · Answer

P(A|B) = P(A U B)/ P(B)

   =  2/36 / 5 / 36
   = 2/5

anonymous · Answer

got it??

anonymous · Answer

erm . how did you get 2/36 and 5/36 ?

anonymous · Answer

P (A U B) means the probability of getting a 2 on one of the dice when uve got a six as the sum

now the cases are (2,4) and (4,2) so only 2 cases out of 36

and the cases of getting sum 6 are 5/36 
so

anonymous · Answer

another way of doing it is

anonymous · Answer

how maqny points give a sum of 6?

anonymous · Answer

?

anonymous · Answer

3 ways

anonymous · Answer

5 ways

1,5 
5,1
3,3
2,4
4,2

anonymous · Answer

oh ya.

anonymous · Answer

so now out of these 5, how many cases r there in which theres a 2 on either die?

anonymous · Answer

2

anonymous · Answer

so there u go

2/5

anonymous · Answer

okay thanks a lot !!! i get it !

amistre64 · Answer

and as an aside:  I believe its:

P(A|B) = P(AnB)/P(B)