In 371 ways Mrs. Sullivan choose two students from 27 to help put away calculators at the end of class
Step-by-step explanation:
let us assume that Mrs.Sullivan wants to choose 2 students from a group of 27 students
So ,in the first choice we have 27 students
In the second choice we have 26 choices
So Mrs.Sullivan has = 27 × 26 = 702 ways
But each group repeated twice,in order to avoid that we will divide the answer by 2
so we will write
= 702 ÷ 2 = 351 ways
This method of calculation is called Combination
