Question:

How many different nine digit numbers can be formed from the number $223355888$ by rearranging its digits so that the odd digits occupy even positions?

Updated On: Jun 18, 2022
  • 16
  • 36
  • 60
  • 180
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The Correct Option is C

Solution and Explanation

$X - X - X - X - X$
The four digits $3,3,5,5$ can be arranged at $(-)$ places in $\frac{4 !}{2 ! 2 !}=6$ ways.
The five digits $2,2,8,8,8$ can be arranged at $( X )$ place in $\frac{5 !}{2 ! 3 !}=10$ ways.
Total number of arrangements is $6 \times 10=60$.
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Concepts Used:

Permutations

A permutation is an arrangement of multiple objects in a particular order taken a few or all at a time. The formula for permutation is as follows:

\(^nP_r = \frac{n!}{(n-r)!}\)

 nPr = permutation

 n = total number of objects

 r = number of objects selected

Types of Permutation

  • Permutation of n different things where repeating is not allowed
  • Permutation of n different things where repeating is allowed
  • Permutation of similar kinds or duplicate objects