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6.Permutation and Combination
medium
How many numbers between $5000$ and $10,000$ can be formed using the digits $1, 2, 3, 4, 5, 6, 7, 8, 9$ each digit appearing not more than once in each number
A
$5{ \times ^8}{P_3}$
B
$5{ \times ^8}{C_3}$
C
$5\;!\;{ \times ^8}{P_3}$
D
$5\;!\;{ \times ^8}{C_3}$
Solution
(a) A number between $5000$ and $10,000$ can have any of the digits $5, 6, 7, 8, 9$ at thousand's place.
So thousand's place can be filled in $5$ ways.
Remaining $3$ places can be filled by the remaining $8$ digits in $^8{P_3}$ ways
. Hence required number = $5{ \times ^8}{P_3}$.
Standard 11
Mathematics