P can do $${1\over 2} $$ of a work in 10 days and Q can do $${1\over 5}$$of the same work in 4 days. In how many days can both finish the work, working together?

Two positive numbers differ by 1280. When the greater number is divided by the smaller number, the quotient is 7 and the remainder is 50. The greater number is:

A person covered some distance at some speed. If he traveled a distance of 3 km / h more, it took him 40 minutes less time. If he had covered the distance at a speed of 2 km / h less, he would have taken 40 minutes more. The distance (in km) is

If the average weight of 6 students is 50 kg; that of 2 students is 51 kg; and that of other 2 students is 55 kg; then the average weight of all students is

Two numbers are in the ratio 3:5. If each number is increased by 10, the ratio becomes 5:7. The numbers are -

A certain sum of money yields Rs. 1261 as compound interest for 3 years at 5% per annum. The sum is: 

A certain number of students from school X appeared in an examination and 30% students failed. 150% more students than those from school X, appeared in the same examination from school Y. If 80% of the total number of students who appeared from X and Y passed, then what is the percentage of students who failed from Y?

A sold a watch to B at a profit of 20%. B sold it to C at 30% profit. C sold it to D at 10% loss. If B's profit is ₹80 more than that of A, then D bought it for: