CAT 2006 — QA Question 20
Answer the following question based on the information given below.
An airline has a certain free luggage allowance and charges for excess luggage at a fixed rate per kg. Two passengers, Raja and Praja have 60 kg of luggage between them, and are charged Rs. 1200 and Rs. 2400 respectively for excess luggage. Had the entire luggage belonged to one of them, the excess luggage charge would have been Rs. 5400.
When you reverse the digits of the number 13, the number increases by 18. How many other two digit numbers increase by 18 when their digits are reversed?
Answer & solution
- A
5
6
- C
7
- D
8
- E
10
Let 10x + y be a two digit number, where x and y are positive single digit integers and x > 0.
Its reverse = 10y + x
Now, |10y + x – 10x – y| = 18
∴ 9 |y – x| = 18
∴ |y – x| = 2
Thus y and x can be (1, 3), (2, 4), (3, 5), (4, 6), (5, 7), (6, 8) and (7, 9)
∴ Other than 13, there are 6 such numbers.
Hence, option (b).