In a market 4 men are standing. The average age of the four before 4years is 45, after some days one man is added and his age is 49. What is the average age of all?

This has to be one of those 'trick' questions:

The logical reasoning behind this problem is that four years ago the average age of the four men was 45 years. Hence, now they will be 45 + 4 = 49 years.

Now since a new man has been added to the group and he is 49 years of age, the group average remains the same.

The average age of all the men is 49 years.