general Maths Puzzle

If a rook and a bishop of a standard chess set are randomly placed on a chessboard, what is the probability that one is attacking the other?
Note that both are different colored pieces.

Read Solution (Total 2)

(1/64)*(14/63) + (1/28)*(7/63) + (1/20)*(9/63) + (1/12)*(11/63) + (1/4)*(13/63) = 2441/30240
15 years agoHelpfull: Yes(1) No(0)

13/36
15 years agoHelpfull: Yes(0) No(0)

general Other Question

onsider the sum: ABC + DEF + GHI = JJJ
If different letters represent different digits, and there are no leading zeros, what does J represent?
A tank can be filled by pipe A in 30 minutes and by pipe B in 24 minutes. Outlet pipe C can empty the full tank in X minutes.
If the tank is empty initially and if all the three pipes A, B and C are opened simultaneously, the tank will NEVER be full. Give the maximal possible value of X.