CAT 2020 Permutations and Combinations Question (Medium)

Question

How many 4-digit numbers, each greater than 1000 and each having all four digits distinct, are there with 7 coming before 3?

Accepted Answer

Step 1 We need 4-digit numbers 1000 with all distinct digits and digits 7 and 3 such that 7 comes before 3. Total digits choose any 4 distinct digits from 0 9 such that - 7 and 3 are both included - All digits are distinct - Number is 4-digit i.e., first digit 0 - In the number, 7 appears before 3 i

CAT 2020

Quantitative

Permutations and Combinations

Medium

$How many 4-digit numbers, each greater than 1000 and each having all four digits distinct, are there with 7 coming before 3?$

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