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How many different samples can be chosen???

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by gmatpup » Sat Dec 24, 2011 9:29 am
If a quality control check is made by inspecting a sample of 2 lightbuls from a box of 12, how many different samples can be chosen?

A. 6
B. 24
C. 36
D. 66
E. 72

Answer is D


Please explain, thank you :)!
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by LalaB » Sat Dec 24, 2011 9:35 am
12C2 =12!/2!*10!=66
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by Anurag@Gurome » Sun Dec 25, 2011 7:43 pm
gmatpup wrote:If a quality control check is made by inspecting a sample of 2 lightbuls from a box of 12, how many different samples can be chosen?

A. 6
B. 24
C. 36
D. 66
E. 72

Answer is D


Please explain, thank you :)!
Samples can be chosen in 12C2 = 12!/[2! * (12 - 2)!] = (12 * 11 * 10!)/[2 * 10!]
= 6 * 11 = 66

The correct answer is D.
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by ArunangsuSahu » Tue Jan 03, 2012 9:55 pm
12C2=66
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by Scott@TargetTestPrep » Tue Jun 26, 2018 5:16 pm
gmatpup wrote:If a quality control check is made by inspecting a sample of 2 lightbuls from a box of 12, how many different samples can be chosen?

A. 6
B. 24
C. 36
D. 66
E. 72
The number of samples that can be chosen is:

12C2 = 12!/(2! x 10!) = (12 x 11)/2! = 66

Answer: D

Scott Woodbury-Stewart
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