Final answer:
To have a gain of 8%, 42 oranges need to be sold per rupee.
Step-by-step explanation:
To find how many oranges per rupee need to be sold to have a gain of 8%, we can first calculate the cost per orange after a 4% loss. Let's assume the cost of one orange is C rupees. We know that 36 oranges are sold per rupee, so the cost per orange is 1/36 rupees.
Therefore, 1/36 rupees is equal to C rupees after a 4% loss.
To find the gain of 8%, we need to determine the cost per orange when the selling price is C rupees. We can set up the equation: 1/36 + (8/100)(1/36) = C.
Solving this equation, we find C to be 1/42 rupees per orange.
Therefore, to have a gain of 8%, we need to sell 1 orange for every 1/42 rupees. So the answer is option b) 42.