Correct Answer  Option 3 : 50%
Given:
Cost price of 8 apples is equal to the selling price of 5 apples
Cost price of 13 oranges is equal to selling price of 10 oranges
Ratio of cost price of 1 apple to 1 orange = 5 : 2
Concept:
Profit% = {(Selling price – Cost price) × 100}/Cost price
Calculation:
Let, cost price of 1 apple = Rs.a
And selling price of 1 apple = Rs.b
According to question,
8 × a = 5 × b
⇒ a/b = 5/8
a = 5x
b = 8x
Let, cost price of 1 orange = Rs.c
And selling price of 1 orange = Rs.d
13 × c = 10 × d
c/d = 10/13
c =10y
d = 13y
Ratio of cost price of 1 apple to 1 orange = 5 : 2
a : c = 5 : 2
5x/10y = 5/2
⇒ x = 5y

Cost price

Selling price

1 Apple

25y

40y

1 Orange

10y

13y

Cost price of (8 Apples + 10 Oranges) = 8 × 25y + 10 × 10y = Rs.300y
Selling price of (8 Apples + 10 Oranges) = 8 × 40y + 10 × 13y = Rs.450y
Profit% = {(Selling price – Cost price) × 100}/Cost price
Profit% = {(450y – 300y) × 100}/300y = 50%
∴ Net profit percent on the sale of 8 apples and 10 oranges is 50%.