Lets say the total number of copies sold is 100
Number of newspaper A copies sold is P and then the newspaper B copies sold is 100 -p
We can form this equation.
\(\frac{R}{100} [ P*1+ 1.25(100-P)] = P *1\)
\(\frac{R}{100}(P + 1.25(100-P) = P\)
R(P+ 125 -1.25P) = 100P
\(125 R – .25RP= 100P\)
\(125R - \frac{1}{4}RP = 100P\)
\(500 R – RP = 400P\)
\(R(500-P) = 400P\)
\(R= \frac{400P}{(500-P)}\\
\)
Option D is the answer
Or as an alternate approach, we can assume values.
Let say, total no of newspapers be 100.
Assume P =60%
Let the No of Newspaper A sold = 60 % of 100= 60
Then no of Newspaper B sold is 40
We assumed P as 60 % because you get 40 as the no of Newspaper B sold and when 40 multiplied by 1.25, you will get an integer and your calculations will be easy (Or you can start by assuming P=20 %)
Revenue from Newspaper A= 60*1 = 60 $
Revenue from Newspaper B = 40*1.25= 50 $
Then R= % revenue from sales of Newspaper A = \(\frac{60}{110}* 100 = 54.54 \)%
(* Use Fraction-% conversion table, 1/11= 9.09 % then 6/11 = 6*9.09= 54.54 %)
In each option, you can substitute P = 60 and check whether you are getting R = 54 %
You don’t need to calculate exact value in each option, instead you can check whether it’s close to
50 % or not
For example, in Option A.
R = 100*60/65 = (60/65) *100
We can straightaway eliminate as its close to 100 %
In Option b,
\(R= 150*60/190 = \frac{90}{190}*100\)
Since 90 is less than 50 % of 190 . we can eliminate option B
in option C ,
\(R= 300*60/315= \frac{180}{315}*100\)
we can eliminate as its more than 55 % of 315
Try to split the percentage as 50% + 5 % of 315 to get approximate value faster.
in Option D,
\(R =400*60/440 = \frac{24}{44 }* 100 = 6/11* 100 = 54.54 \)%
Option D is the answer
Thanks,
Clifin J FrancisGMAT SME