If a quality control check is made inspecting a sample of 2 light bulbs from a box of 13 lighbulbs, how many different samples can be chosen?
Choose the correct answer:
A) 6	B) 24	C) 36	D) 66	E) 78
Try using the formula for combinations:   n!/r!(n-r)!   13!/2!(13-2)!   13!/2!*11!    13*12/2*1= 
<gadget id="calculator"> 13*12/2*1</gadget>
<output>78</output>
78   78
<result>E</result>
If a quality control check is made inspecting a sample of 2 light bulbs from a box of 13 lighbulbs, how many different samples can be chosen?