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The probability that the sum of squares of two non-negative integers is divisible by 5 is(a) 7/25(b) 8/25(c) 9/25(d) 2/25 |
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Answer» Correct option (c) 9/25 Explanation: Let two non-negative integers be x & y such that x = 5a + α and y = 5b + β where 0 ≤ α, ≤ β New, x2 + y2 = 25(a2 + b2 ) + 10(aα + bβ)+ α2 + β2 α2 + β2 should be divisible by 5 (α ,β) can have ordered pairs as {(0,0), (1,2), (2,1), (1,3), (3,1), (2,4), (4,2), (3,4), (4,3)} = 9 ways required probability is 9/25 |
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