Let n be a four-digit integer in which all the digits are different. If x is number of odd integers and y is number of even integers, then
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a
x < y
b
x > y
c
x + y = 4500
d
|x - y| = 1288
answer is A.
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Detailed Solution
When n is odd:The number of such numbers is 8 x 8 x 7 x 5 = 2240.When n is even:If unit's place is filled with 0, then the total number is 9 x 8 x 7 = 504.If unit's place is not filled with 0, then the total number is 8 x 8 x 7 x 4 = 1792.Hence, the total number of even numbers is y = 504 + 1792 = 2296.