Four buses run between Bhopal and Gwalior. If a man goes from Gwalior to Bhopal by a bus and comes back to Gwalior by another bus, find the total possible ways.

There are 10 buses running between two towns X and Y. In how many ways can a mango from X to Y and return by a different bus ?

There are 4 bus routes between A and B and 3 bus routes between B and C. A man can travel round trip in number of ways by bus from A to C via B. If he does not want to use a bus route more than once, in how many ways can he make round trip?

If there are 20 buses playing between places A and B, in how many ways can a round trip from A be made if the return journey was made on: i. the same bus, ii. a different bus.

A man of mass m runs without sliding from rest from one end of a boat of mass M and length l with an acceleration a relative to the boat. If the friction between water and boat is neglected find the a. acceleration of CM of the system (M+m) b. acceleration of the man and boat c. position of man at the time when he reaches to other end of the boat d. frictional force e. work done by friction on boat. f. total work done by friction. g. velocities of man and boat when the man reaches other end of the boat. h. work down by man