Question

A lock is opened using a sequence of three numbers. the numbers range from 0 to 39, inclusive, and cannot be repeated within the sequence. what is the probability that all the numbers in the sequence are even? express your answer as a percent and round to the nearest whole number.

Answer 1

10%.

Explanation:

There are a total of 40 numbers.

Number of permutations of 3 numbers from 40

= 40 P 3

= 40! / (40-3)!

= 59,280.

The total of even numbers is (38 - 2) / 2 + 1 = 19.

Number of permutations of 3

= 19P 3

= 5814

So Prob(all even) = 5814/59280

= 0.098077

= 9.8%

= 10% to nearest whole number.