1) In a hotel, rooms are numbered from 101 to 550. A room is chosen at random. What is the probability that room number starts with 1, 2 or 3 and ends with 4, 5 or 6?

Answer
There are total 450 rooms.
Out of which 299 room number starts with either 1, 2 or 3. (as room number 100
is not there) Now out of those 299 rooms only 90 room numbers end with 4, 5 or
6.So the probability is 90/450 i.e. 1/5 or 0.20.

2) What is the four-digit number in which the first digit is 1/3 of the second, the third is the sum of the first and second, and the last is three times the second?

Answer
The 4 digit number is 1349.

3) Difference between Bholu's and Molu's age is 2 years and the difference between Molu's and Kolu's age is 5 years. What is the maximum possible value of the sum of the difference in their ages, taken two at a time?

Answer
The maximum possible value of the sum of the difference in their ages -
taken two at a time - is 14 years.

4) A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is
396.What is the sum of the three digits?

Answer
The required number is 236 and the sum is 11.