A cube is painted with red colour and then cut into 64 small
identical cubes. If two cubes are picked randomly from the heap of 64
cubes, what is the probability that both of them have exactly two faces
painted red?

1) 23/168
2) 1/4
3) 31/163
4) 47/84

• 23/168
  
  Number of cubes with exactly two faces painted red = 2*12=24.
  probability that both of them have exactly two faces painted red =
  (24/64)*(23/63) = 23/168
• 11 years agoHelpfull: Yes(1) No(0)