25 buses are running between two places P and Q. In how many ways can a person go from P to Q and return by a different bus?
Choose the correct option:  A) None of these  B) 600  C) 12  D) 24  E) 42
Explanation :   He can go in any bus out of the 25 buses.   Hence He can go in 25 ways.   Since he can not come back in the same bus that he used for travelling,   He can return in 24 ways.   Total number of ways = 25 x 24 = 600. Answer : Option 600
<result>B</result>
25 buses are running between two places P and Q. In how many ways can a person go from P to Q and return by a different bus?