Mathematics - Permutation & Combination Question with Solution | TestHub

MathematicsPermutation & CombinationDivision of Identical itemsMedium2 minQB

MathematicsMediumsingle choice

The number of seven digit integers, with sum of the digits equal to 9 and using at least one of the digits

1, 2, 3 only is

Answer:

Solution:

Number of 7 digit numbers with $3, 1, 1, 1, 1, 1, 1 = \frac{7 !}{6 !} = 7$

Number of 7 digit numbers with $2, 2, 1, 1, 1, 1, 1 = \frac{7 !}{5 ! 2 !} = 21$

Stream:JEESubject:MathematicsTopic:Permutation & CombinationSubtopic:Division of Identical items

⏱ 2mℹ️ Source: QB

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