Question

A bicycle lock requires a two-digit code of numbers 1 through 9, and any digit may be used only once. Which

expression would determine the probability that both digits are even?

Answer 1

16/81

Explanation:

the probability that they are both even is the probability that the first is even then multiplied by the probability that the second is even:

Formula is:

P(A and B) = P(A) * P(B)

the P(something) is probability of something

so

1 digit: P(even) = 4 possibilities (2,4,6,8) out of 9 total (1,2,3,4,5,6,7,8,9) = 4/9

2 digit:P(even) = 4 possibilities (2,4,6,8) out of 9 total (1,2,3,4,5,6,7,8,9) = 4/9

which is 4/9 * 4/9 =16/81