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:
- 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 $=4+18+72+216=310$
