Permutations and Combinations 1 Question 1

1. The number of four-digit numbers strictly greater than 4321 that can be formed using the digits $0,1,2,3,4,5$ (repetition of digits is allowed) is

(2019 Main, 8 April II)

(a) 306

(b) 310

(c) 360

(d) 288

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Answer:

Correct Answer: 1. (b)

Solution:

  1. Following are the cases in which the 4-digit numbers strictly greater than 4321 can be formed using digits 0 , $1,2,3,4,5$ (repetition of digits is allowed)

Case-I

$$ 2 / 3 / 4 / 5 \longrightarrow 4 \text { ways } 4 \text { numbers } $$

Case-IV

So, required total numbers $=4+18+72+216=310$



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