Ssuming that no one is born on feb. 29 (leap day), how many people should be selected to guarantee that at least 8 were born on the same day, not considering the year?

197


Explanation:

There are 28 days in February for non-leap years. We would need to select at least 28*7+1 = 197 people so that we are guaranteed that at least 8 people were born on the same day.

The worst case scenario is that we pick 7 people born on feb 1, then 7 people for feb 2, and so on til we get up to feb 28. This is a total of 28*7 = 196 people. That extra person will have to somewhere in the calendar for feb. Since its not that leapday, this extra person will make a group of 8. So that's why we need to select at least 197 people (aka 197 people or more).