Correct Answer - Option 4 : 12.96%
Given:
The cost price of the two books is in the ratio of 2 ∶ 3.
Marked price over cost price is 30% and 40% for the respective books.
Each book is given after successive discounts of 20%.
Concepts used:
M.P. = S.P. + Discount
Discount % = Discount/M.P. × 100
Calculation:
Let cost price of two books be 2x and 3x.
⇒ Total C.P. of 2 books = 2x + 3x = 5x
⇒ M.P. of 1st book = 2x + (2x × 30%) = 13x/5
⇒ M.P. of 2nd book = 3x + (3x × 40%) = 21x/5
Each book is given after successive discounts of 20%.
⇒ First successive discounts on 1st book = 13x/5 × 20% = 13x/25
⇒ Second successive discount on 1st book = (13x/5 – 13x/25) × 20% = 52x/125
⇒ S.P. of 1st book = 13x/5 – (13x/25) – (52x/125) = 208x/125
⇒ First successive discounts on 2nd book = 21x/5 × 20% = 21x/25
⇒ Second successive discount = (21x/5 – 21x/25) × 20% = 84x/125
⇒ S.P. of 2nd book = 21x/5 – (21x/25) – (84x/125) = 336x/125
⇒ Total S.P. = 208x/125 + 336x/125 = 544x/125
As C.P. > S.P.
⇒ Overall loss % = (5x – 544x/125)/5x × 100 = 12.96%
∴ Overall loss % is equal to 12.96%.