Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationFundamental PrincipleHard2 minQB

MathematicsHardsingle choice

How many ordered triplets $(a, b, c)$ of positive integers less than 10 have product $ab c$ divisible by 20 ?

Options:

Answer:

Solution:

With exactly one entry 5 : two even entries contribute 48 , and one multiple of 4 with one odd entry contributes 48 . With exactly two entries 5 and the remaining entry divisible by 4, there are 6 more. Total $48 + 48 + 6 = 102$ .

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:Fundamental Principle

⏱ 2mℹ️ Source: QB

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