A Community College hosts an alumni reunion and exactly 300 people attend the reunion. Each guest in attendance is asked to enter their birth date on a laptop during the sign-in registration. The computer tracks not only the year and month that each person was born, but also determines the day of the week that their birthday fell on. As it turns out, the guests can be partitioned so that there are exactly the same number born in each of the decades of the1950’s, 60’s, 70’s, 80’s, and 90’s.

a.) Must there be at least one day of the week for which at least 43people were born on that day (at least 43 born on a Monday, or at least 43 born on a Thursday, etc.)? Explain your reasoning using the PIGEON-HOLE PRINCIPLE

I'm not really sure were to start. Ive tried looking at notes but i'm not that good at solving word problems.