Question

Using the digits 3, 4, 5, 6 and 7, without repetitions, calculate the

number of 4-digit numbers that are greater than 5 000 that can be
formed.
Jawapan:
Answer:​

Answer 1

72

Explanation:

There are five possible digits to choose from: 3, 4, 5, 6, and 7.

The number must be greater than 5000, so there are 3 possibilities for the first digit: 5, 6, or 7.

There's no repetition, so the second digit is one of 4 remaining possible digits.

That leaves 3 possible digits for the third digit. And 2 possible digits for the fourth digit.

So the number of possible four-digit numbers that can be formed is:

3 × 4 × 3 × 2 = 72

Answer 2

`1\cdot4\cdot3\cdot2+2\cdot4\cdot3\cdot2=24+48=72`