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Ask iit jee aieee pet cbse icse state board community Community Discussion Question: per com problem........
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avik987 (0)

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a family consists of a grandfather , 5 sons and 8 grandchildren. they r to be seated in a row for a dinner. the grandchildren wish to occupy the four seats at each end of the row and the grandfather refuses to have a grandchild besides him. In how many ways can the family be made to sit ?
 
my solution.............
total no of seats = 14
 
8 grandchildren can be made to seat in 8! ways .
grand father can be made to sit in 5 - 1 ways.......
and the remaing seat can be filled in 5! ways.
so total  = 8! * 4 * 5!
 
but ans is 4! * 4 * 5!     plzzz help out....................
 
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in how many ways can a mixed doubels game of tennis can be arranged from 5 married couples, if no husband and wife play in the same game?
 
my solution..........
 
let two teams be A n B
for team A 5 husbands can be selected in 5 ways and 4 wifes can be selected in 4 ways........
for team B 4 husbands can be selected in 4 ways n 3 wifes can be selected in 3ways
so total ways is 5*4*4*3 = 240
but answer in 60
plzzzzz guys help out...........
    
vineetnegi (107)

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Olaaa!! Perrrfect answer. 19  [25 rates]

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You may not like using multinomial th to much but lately i have been fancied by its versutality
 
your
ans
make groups
y-------male
x--------female
(1+x+y)(1+x+y)....5times
(1+x+y)^5
 
(1+x)^5+5(1+x)^4y+10(1+x)^3y^2+10(1+x)^2y^3+5(1+x)y^4+y^5
 
coefficient of x^2y^2
 
= see only third term=3*10=30
in each case you have selected 2 male and two female
2 teams can be made out of four in 2 ways
 
so ans
=30*2=60

those who dont believe in god closes the gates of miracles in their life
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