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CBSE XI
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Permutations and Combinations
A seven-digit number made up of all distinct digits 8,7,6,4,2,x and y is divisible by 3.Then possible number of order pair (x,y) is
$\begin{array}{1 1}(A)\;4\\(B)\;8\\(C)\;2\\(D)\;\text{None of these}\end{array} $
cbse
math
class11
ch7
permutations-and-combinations
additionalproblem
q2
sec-b
medium
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asked
May 19, 2014
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1 Answer
$8,7,6,4,2,x$ and $y$
Any number is divisible by 3,if sum of digits is divisible by 3
(i.e) $x+y+27$ is divisible by 3
$x$ and $y$ can take values from 0,1,3,5,9
Possible pairs (5,1),(3,0),(9,0),(9,3) and (1,5),(0,3),(0,9),(3,9)
Hence (B) is the correct answer.
answered
May 19, 2014
by
sreemathi.v
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