A penny collection contains twelve 1967 pennies, seven 1968 pennies, and eleven 1971 pennies. If you are to pick some pennies without looking at the dates, hoe many must you pick to be sure of getting at least five prennies from the same year?

The number of pennies to be picked to be sure of getting at least five pennies from the same year.

Given information:

A penny collection contains twelve 1967 pennies seven 1968 pennies and eleven 1971 pennies.

Calculation:

Using the pigeonhole principle- the pigeonhole principle states that there must be at least one box which will contain two or more objects if n+1 objects are put in n boxes.

There are total 3 years that means there must be at least n+1=3+1=4 pennies must be picked in order to say that any two belongs to the same year