If a quality control check is made inspecting a sample of 2 light bulbs from a box of 11 lighbulbs, how many different samples can be chosen?
Answers: A) 6 B) 24 C) 55 D) 66 E) 72
Try using the formula for combinations:   n!/r!(n-r)!   11!/2!(11-2)!   11!/2!*9!    11*10/2*1= 
<gadget id="calculator"> 11*10/2*1</gadget>
<output>55</output>
55   55
<result>C</result>
If a quality control check is made inspecting a sample of 2 light bulbs from a box of 11 lighbulbs, how many different samples can be chosen?