A girl is twice as old as her brother and half as old as her father. In 50 years, her brother will be half as old as his father. How old is the daughter now?

In a town, there are four houses located at different distances from each other. Following are the distances:

The third house is 60 meters apart from the first house.
The fourth house is 40 meters apart from the second house.
The third house is 10 meters nearer to the fourth house than it is to the second house.

Can you find out the distance between the fourth and the first house?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Rectify the following equality 101 - 102 = 1 by moving just one digit.

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

Can you find a seven digit number which describes itself. The first digit is the number of zeros in the number. The second digit is the number of ones in the number, etc. For example, in the number 21200, there are 2 zeros, 1 one, 2 twos, 0 threes and 0 fours.

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?