The number of different seven digit numbers that can be written using only three digits 1, 2 &3 under the condition that the digit 2 occurs exactly twice in each number.A. `""^(7)P_(5).2^(5)`B. `""^(7)C_(2).2^(5)`C. `""^(7)C_(2).5^(2)`D. none of these

The number of different seven digit numbers that can be written using

1.	The number of different seven digit numbers that can be written using only three digits 1, 2 &3 under the condition that the digit 2 occurs exactly twice in each number.A. `""^(7)P_(5).2^(5)`B. `""^(7)C_(2).2^(5)`C. `""^(7)C_(2).5^(2)`D. none of these
Answer» Choose any two of the seven digits (in the seven digit number). This may be done in `""^(7)C_(2)` ways. Put 2 in these two digits. The remaining 5 digits may be arranged using 1 and 3 in `2^(5)` ways. So, required number of numbers = `""^(7)C_(2)xx2^(5)`.

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The number of different seven digit numbers that can be written using only three digits 1, 2 &3 under the condition that the digit 2 occurs exactly twice in each number.A. `""^(7)P_(5).2^(5)`B. `""^(7)C_(2).2^(5)`C. `""^(7)C_(2).5^(2)`D. none of these

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