Today's quant question 4

Question

In question 4 there is given the average of three after increasing first and second power by same percentage equals third 
But in solution it has taken average of two instead of average of three

nav · Accepted Answer

actually it is average of 3 values only, just written as a shortcut
according to question, 7x, 9x, 10x are initial values and after %increase (let p%), final values are First=7xp, Second=9xp, Third=10x.
now average condition gives  
=> Third = (First + Second + Third)/3
=> 3(Third) = First + Second + Third
=> 3(Third) - Third = First + Second
=> 2(Third) = First + Second
=> Third = (First + Second)/2      {as given in solution}
=> 10x = (7xp + 9xp)/2
=> 2(10x) = 16xp
=> 20x = 16xp
=> p = 5/4 = 1.25 = 25% increase

hope this helps :)

Today's quant question 4

1 Answer