An urn contains 25 balls of which 10 balls bear a mark "X" and the remaining 15 bear a mark T. A ball is drawn at random from the urn, its mark is noted down and it is replaced. If 6 balls are drawn in this way, find the probability that (i) all

Answer

(i) `((2)/(5))^(6)` (ii) `7((2)/(5))^(4)` (iii) `1-((2)/(5))^(6)` (iv) `20((6)/(25))^(3)`.