A tank is fitted with two taps. The first tap can fill the tank completely in 45 minutes and the second tap can empty the full tank in one hour. If both the taps are opened alternately for one minute, then in how many hours the empty tank will be filled completely?

Prakash, Sunil and Anil started a business jointly investing Rs. 11 lakhs, Rs. 16.5 lakhs and Rs 8.25 lakhs respectively. The profit earned by them in the business at the end of three years was Rs. 19.5 lakhs. What will be the 50% of Anil's share in the profit? 

The breadth of a rectangular hall is three - fourth of its length. If the area of the floor is 768 sq. m., then the difference between the length and breadth of the hall is: 

A motorboat, whose speed is 45 km./hr. in still water goes 180 km. downstream and comes back in a total of 9 hours. The speed of the stream (in km/hr.) is-

Two trains 108 m and 112 m in length are running towards each other on the parallel lines at a speed of 45 km/hr and 54 km/hr respectively. To cross each other after they meet, it will take

A and B together can plough a field in 10 hours but by himself A requires 15 hours. How long would B take to plough the same field?

Which is the smallest prime number?