Question

A bag contains 11 blocks numbered from 1 to 11. Two blocks are selected from the bag at the same time.

Let event E = the two numbers are NOT even.

How many outcomes are in the complement of E?

A)
10


B)
20


C)
70


D)
90

Answer 1

The answer is A= 10

Explanation:

The complement of E is when the two numbers are even.

(2, 4), (2, 6), (2, 8), (2, 10), (4, 6), (4, 8), (4, 10), (6, 8), (6, 10), (8, 10)

Thus, there are 10 outcomes where the numbers are even.

Answer 2

Event E is the two numbers are not even.
The complement of event E is the two numbers are even.
The number of outcomes of the complement of event E is 5 * 4 = 20, but since the outcome 2, 4 is the same as the outcome 4, 2, you need to divide the number of outcomes by 2.

Answer: 10