145k views
4 votes
Nine disks are numbered from 1 to 9 and placed in a box. One disk is

selected at random and not replaced. Another disk is randomly selected.
What is the probability of selecting two even numbers? ​

1 Answer

4 votes

The probability of selecting two even numbers is 1/6.

Explanation:

Nine disks are numbered from 1 to 9 and placed in a box.

The total number of disks = 9

The question is asked to find the probability of selecting two even numbers.

  • We know that, the disks in the box are {1,2,3,4,5,6,7,8,9}.
  • The even number disks are {2,4,6,8}.

The number of even number disks = 4 disks.

To find the probability of selecting two even numbers without replacement :

P (first even disk) = No.of even disks / Total disks

⇒ 4 / 9

P (second even disk) = No.of remaining even disks / Total disks

⇒ 3 / 8

P (two even disks without replacement) = 4/9 × 3/8

⇒ 12 / 72

⇒ 1 / 6

∴ The probability of selecting two even numbers is 1/6.

User Christk
by
4.6k points