Question

the average of the ages of Renuka and usha is 25 years the average of Ages of Usha and Medha is 21 years if the average age of all the three is 24 years what is the average of the ages of Renuka and Medha ? ..
pls answer ..
it's urgent

Answer 1

There could be two ways of solving this prolem. One mathematically and other theoretically. So here it goes -

Mathematically : We can write average as (A+B+C)/3 = 26 or,

A+B+C = 78

Similarly, we can see average of A&C.

(A+C)/2 = 29 or,

(A+C) = 58

Now you can solve it easily.

(A+B+C)-(A+C) = 78–58 = 20.

So age of B is 20 years.

Theoretically : If you observe you'll see when B's age is not considered the average for A&C increases by 3. This means that if age of all three had same the average(of A&C) would not have been increased by 3 due to the removal of B. So if there is increase in 3 years in average of A&C, this means that there should be a decrease of 6 years(3 due to A & 3 due to C) in the age of B itself. If B's average age was 26, then the actual age of B is (26–6 = 20).

Hope it helps.

Thanks for A2A.