If the probability of an event is [tex]\frac{2}{7}[/tex], what must be the probability of its complement?

A. [tex]\frac{1}{7}[/tex]
B. [tex]\frac{2}{7}[/tex]
C. [tex]\frac{4}{7}[/tex]
D. [tex]\frac{5}{7}[/tex]



Answer :

To find the probability of the complement of an event, we need to understand that the sum of the probabilities of an event and its complement must equal 1. This is a fundamental concept in probability theory.

1. Given:
- The probability of the event [tex]\( P(\text{Event}) = \frac{2}{7} \)[/tex].

2. The probability of the complement of the event, [tex]\( P(\text{Complement}) \)[/tex], is calculated as:
[tex]\[ P(\text{Complement}) = 1 - P(\text{Event}) \][/tex]

3. Substitute the given probability into the equation:
[tex]\[ P(\text{Complement}) = 1 - \frac{2}{7} \][/tex]

4. To perform the subtraction, convert 1 to a fraction with a denominator of 7:
[tex]\[ 1 = \frac{7}{7} \][/tex]

5. Now, subtract the fractions:
[tex]\[ P(\text{Complement}) = \frac{7}{7} - \frac{2}{7} = \frac{7 - 2}{7} = \frac{5}{7} \][/tex]

Thus, the probability of the complement of the event is [tex]\(\frac{5}{7}\)[/tex].

Among the provided options, the correct answer is:
[tex]\(\frac{5}{7}\)[/tex].