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Saturday, September 22, 2007

A-Math P & C Qn!

The no. of applicants for a job is 15. (i)Calculate the no. of ways in which 6 applicants can be selceted for the interview.

The six selected applicants on a particular day. (ii)Caluculate the no. of ways in which the order of the six interviews can be arranged.

Of the 6 applicants, 3 have backgrounds in business, 2 have backgrounds in education and 1 has a background in recreation. Calculate the number of ways in which the order of the 6 interviews can be arranged, when applicants having the same background are interviewed in succesion.


Who's up for this challenge?



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Of the 6 applicants, 3 have backgrounds in business, 2 have backgrounds in education and 1 has a background in recreation. Calculate the number of ways in which the order of the 6 interviews can be arranged, when applicants having the same background are interviewed in succesion.


BBB EE R

So there are 3 groups of people and there are 3! ways of arranging these 3 groups
Within BBB group, there are 3! ways of arrange these 3 B people, similar within EE group, there are 2! ways of arrange these 2E people
so Total = Arrange Big Groups * Arrange within each group = 3! * 3! * 2!

2 comments:

lijun(: said...

hey..

my amaths really isn't strong, so i hope you'll help me and correct my mistakes. thanks.

anyway. here are my answers:

(i)no. of ways in which 6 applicants can be selceted for the interview = 15C6 = 5005

(ii)no. of ways in which the order of the six interviews can be arranged = 6! = 720

number of ways in which the order of the 6 interviews can be arranged, when applicants having the same background are interviewed in succesion = 3!X2!X3! = 72


i'm quite doubtful of the last answer. haha. but i decided to try anyway. (:

alwaysLovely said...

well done!
Good job!