father and his son are celebrating their 10th birthday in the same week. What can be the maximum age difference between them?

Answer 1

This is a weird question, but Im going to assume that the father was born in a leap year in order to be able to answer.

The son is 10 today, thats the easier part.

Now what about the father. He presumably had his "first" birthday at age 1 and then every 4 years thereafter. (Of course his first could be at ages 1, 2, 3 or 4 depending what year he was born, but we wanted the earliest possible so we went with one.) So know it follows dad had his 10 "real" birthdays at ages 1, 5, 9, 13, 17, 21, 25, 29, 33, 37.

Therefore today dad is 37, but is celebrating his "birthday" for only the 10th time.

The age difference is therefore 27 years, 37-10