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TS EAMCET · Maths · Permutation Combination

By using the non-zero digits, the number of 5 digit numbers that can be formed so that each number has largest digit in its middle place and the digits in the number are different is

  1. A \(\sum_{r=4}^9{ }^r P_4\)
  2. B \(\sum_{r=4}^8{ }^r P_4-\sum_{r=4}^8{ }^r P_3\)
  3. C \(\sum_{r=4}^8{ }^r P_3\)
  4. D \(\sum_{r=4}^8{ }_r^r P_4\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\sum_{r=4}^8{ }_r^r P_4\)

Step-by-step Solution

Detailed explanation

Since, the largest digit is in the middle, the middle digit is greater than or equal to 5 , the number of numbers with 5 in the middle \(={ }^4 P_4\) ( \(\because\) the four places are to be filled by \(1,2,3,4\) ) Similarly, the number of numbers with 6 in the middle…