How many numbers must be selected from the set left curly bracket 1 comma 2 comma 3 comma 4 comma 5 comma 6 comma 7 comma 8 comma 9 comma 10 right curly bracket in order to guarantee that at least one pair adds up to 11

6 numbers

Step-by-step explanation:

Given

Required

Pairs that add up to 11

The pairs are:

In the above set, we have:

Using pigeonhole principle

This principle implies that, there is at least 1 more pair.

Hence, the numbers that must be selected to guarantee the required sum of 11 is:

--- The 1 represents (at least 1 more)

step-by-step explanation: