Challenge Prelims V1.0 – Day 19 – CSAT Paper

1. There are large number of silver coins weighing 2 gm, 5 gm, 10 gm, 25 gm, 50 gm each. Consider the following statements:

1. To buy 78 gm of coins one must buy at least 7 coins
2. To weigh 78 gm using these coins one can use less than 7 coins

Which of the statements given above is/are correct?

2. How many pairs of natural numbers are there such that the difference between their squares is 120?

3. The square of the sum of two natural numbers is 4489. The square of their difference is 361. Then what is the sum of the squares of those numbers?

4. How many pairs of integers exist such that the difference between their product and sum is 72?

5. A buyer purchased few books of equal value for Rs 720. If the value of each were Rs 2 less than the price at which buyer originally bought, she could have purchased 4 more books. Then how many books did she originally purchased?