hai every body... i still stuck until now for the following problem. hope somebody can guide me.
A box contains 5 black cubes and 3 red cubes. Two cube are drawn at random from the box. find the probability that :
(a) both cubes are black
(b) both cubes are the same colour
(c) both cubes are different colours
5/14, 13/18 ( i also confuse this ans for which question (a)/ (b) or (c)
(a) P( both cubes are black ) = P (Black,Black)
= 5/8 * 5/8
(b) P (both cubes are the same colour) = P (Black,Black) + P (Red,Red)
= 25/64 + 3/8*3/8
= 25/64 + 9/64
Remarks: base on my calculation it look like it wrong when i compare it with the given ans..