A motor boat goes 20 km downstream and comes back to the starting point in 6 hours. If the speed of the boat in still water is 12 km/h, then the speed of the stream is :

A swimmer's speed in swimming pool is 6 km/hr. He swims between two points in a river and returns back to the starting point. He took 24 minutes more to cover the distance upstream than downstream. If the speed of the stream is 4 km/hr, then the distance between two points is:

A boat takes 6 hr 25 minutes to row upstream a certain distance with a speed which is 14.4 times that of the river current. The time taken by the boat to row down the same distance with same speed is:

The quantity of water that must be added to 36 litres of pure milk at $1\frac{1}{2}$ litres for Rs. 75 so as to have mixture worth Rs. 40 a litre is :

In a 1000 m race P beats Q by 100 m and in the same race Q beats R by 200 m. By what distance does P beat R?

The set of all positive integers less than 50 forming the equivalence class of 8 for modulo 11 is :

A, B and C entered in a partnership business. They invested their capitals in the ratio of $\frac{4}{3} : \frac{5}{2} : \frac{6}{5}$. After 5 months, B invested 40% more than what he had invested earlier. If the total profit at the end of one year was Rs 50,550, then how much profit did A earn?