Correct Answer - Option 1 : 50
Given:
5 years ago,
Average of 4 persons was 40 years.
Now,
Average of 5 persons is 46 years.
Formula Used:
Average = Sum of all observations/Total number of observations
Calclulation:
Five years ago,
The average of 4 persons was 40
⇒ 40 = Sum of ages of 4 persons/4
⇒ Sum of ages of 4 persons = 40 × 4
⇒ Sum of ages of 4 persons = 160 years
Present age = Age of a person 5 years ago + 5 year
⇒ The sum of current ages of all 4 members is,
⇒ 160 + 4 × 5
⇒ 160 + 20
⇒ 180 years.
Now 5th member is added and the average is 46 years.
⇒ 46 = Sum of ages of all 5 persons/5
⇒ Sum of ages of all 5 persons = 46 × 5
⇒ Sum of ages of all 5 persons = 230 years.
The age of 5th is,
⇒ 230 – 180
⇒ 50 years
∴ The age of the 5th person is 50 years.