here is the question :
20 people are at the firm. 5 to be sent away on business. how many groups can be formed providing that Pres, VP and Accountant cant go altogether among 5.
Here is the way i approached it:
20-3(that cant go) = 17 than a simple combination pick 17!/(5!*12!)
here is the way Gmat Club solved it:
total number of combinations =20!/5!15!
restricting number of combinations with 3 that cant go 17!/)(2!15!)
than subctracting total minus restricted..
why cant the first method work i thought its the same?
whats the reasoning? Thanks in advance!!
This question is poorly worded. Does this mean that NONE of the 3 can go? or does this mean that any none, one, or two of the 3 can go so long as all 3 don't go?
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993