Join 60,000+ competitive exam aspirants
The average age of 10 men is 30 years. If two men aged 20 and 24 are replaced by two new men, the average age becomes 32. What is the average age of the two new men?
34
35
36
37
35
Sum of new ages = Sum of replaced ages + (Change in average ├ЧTotal number of men).
Number of men = 10, Initial average age = 30 years, Replaced ages = 24 and 26 years, New average age = 32 years
AnewтАЛ=2SreplacedтАЛ+(╬ФA├Чn)тАЛ
Sum of new ages = Sum of replaced ages + (Change in average ├ЧTotal number of men).
Forgetting to multiply the change in average by the total number of men before adding it to the sum of the replaced ages.
Calculate Initial Total Age
Find the total age of the 10 men using the initial average of 30 years.
TinitialтАЛ=10├Ч30=300
Determine Remaining Age After Replacement
Subtract the ages of the two men (24 and 26) who left the group from the initial total age.
TremainingтАЛ=300тИТ24тИТ26=250
Calculate New Total Age
Calculate the new total age of the 10 men based on the new average age of 32 years.
TnewтАЛ=10├Ч32=320
Find Average of Two New Men
Subtract remaining age from new total age to get the sum of new men, then divide by 2.
AnewтАЛ=2320тИТ250тАЛ=270тАЛ=35
B is correct because the calculated average age of the two new men is 35 years.
This weighted average concept is widely applicable in data interpretation, mixtures, and alligation problems in competitive exams.