16. Four persons P, Q, R and S are working in the same company. The sum of the incomes of P and Q is more than that of R and S together. The sum of the incomes of P and R is the same as the sum of the incomes of Q and S. Moreover, P earns half as much as the sum of the incomes of Q and S. Which one of the following persons has the highest income ?

17. A student is practising some math problems. In the first hour he solves 3 problems, in the second hour he solves 5 problems, in the third hour he solves 7 problems and so on. What is the total number of problems solved by him in 10 hours ?

18. The cost price of an article X is 200% more than that of Y, and 75% less than that of Z. The selling price of the article X is 500% more than that of Z. If the profit on article X is twice that on Y, and is twice the loss on Z, then what is the ratio of profit on article Y to its cost price ?

19. Abhishek invests < 10,000 at a simple interest of 6% per annum for y years. The interest is paid annually, of which Abhishek spends half and keeps the remaining in cash, in a box labelled B at home. To begin with, B had no money in it, and nothing else, except half of these interest incomes is added to the box. No money is removed from B. After y years, if the cash in B is < 2,400, then y =

20. A rectangular floor of dimensions 10' * 8' (120" * 96") has to be tiled using the same type of square tiles. Square tiles are available in various dimensions 1", 2", 3", 4", …, 48". What is the size of the largest square tile that can be used to tile the floor completely, without breaking any tile ?