A swimmer can swim 68 km downstream and 45 km upstream in 9 hours and he will take 2 hours more to swim 51 km downstream and 72 km upstream. Find the speed of the swimmer in still water.

The product of two numbers is 2028 and their HCF is 13. The number of such pair is-

The average weight of A B and C is 40 kg . if the average weight of A and B be 48 kg and that of B and C be 45 kg , then find the weight of B ?

A bag contains 3 white balls and 2 black balls. Another bag contains 2 white and 4 black balls. A bag and a ball are picked random. The probability that the ball will be white is:

40% of the employees in a factory are workers. All the remaining employees are executives. The annual income of each worker is Rs. 39000. The annual income of each executive is Rs. 42000. What is the average annual income of all the employees in the factory together?

A work is done by three person A, B and C. A alone takes 10 hours to complete the work but B and C working together takes 4 hours, for the completion of the same work. If all of them worked together and completed 14 times of the work, then how many hours have they worked?

Water flows into a tank which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m x 0.2m) at 20 km/h. In what time will the water level be 8 m?

Ten different letters of alphabet are given, words with 5 letters are formed from these given letters. Then, how many such words can be formed which have at least one letter repeated ?