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AP EAMCET · Maths · Permutation Combination

Four digit numbers with all digits distinct are formed using the digits \(1,2,3,4,5,6,7\) in all possible ways. If \(p\) is the total number of numbers thus formed and \(q\) is the number of numbers greater than 3400 among them, then \(p: q=\)

  1. A \(3: 2\)
  2. B \(4: 3\)
  3. C \(6: 5\)
  4. D \(7: 4\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(3: 2\)

Step-by-step Solution

Detailed explanation

\(p=\) Total four digit number's formed using \(1,2,3,4\), \(5,6,7={ }^7 C_4 \times 4!=\frac{7!4!}{3!4!}=840\) For number greater than 3400 , Numbers starting with 3,4 are \(={ }^5 C_2 \times 2!=20\) Now, first digit can be \(4,5,6,7={ }^4 C_1 \times{ }^6 C_3 \times 3!=480\)…