Percentages: Question1 - Effects of Decrease in Selling Price on Profit

The profit centre of myFATutor has shown that the sales volume of its product will increase by 25% in a particular month if selling prices are reduced by 15%.
If the selling prices are actually reduced as forecast, calculate the expected increase in revenue of myFATutor for the month

Sol1

Revenue is computed as quantity × price

R = Q × P

If Q increases by 25% and P decrease by 15%,

It follows that the new quantity

nQ = 100% - 25% =  75%  

and new price 

nP  =  100% - 15% =  85%

New Revenue = nQ x nP = 125% × 85%

New Revenue  = 1.0625

Thus, we say that revenue will increase by 6.25% Expected increase in revenue is 6.25%