Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationFundamental PrincipleMedium2 minQB

MathematicsMediumsingle choice

The number of positive integers $\leq 100000$ which contain exactly one 2, one 5 and one 7 in its decimal representation is

Answer:

Solution:

Take 5 gaps -------

The digit '2' can occupy any of 5 places

The digit '5' ca occupy any of 4 places

The digit '7' can occupy any of 3 places

Remaining 2 places in $7 \times 7$ ways

Total ways $= 5 \times 4 \times 3 \times 7 \times 7 = 2940$

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

⏱ 2mℹ️ Source: QB

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