9
10
10.1
11
Answer is Wrong!
Answer is Right!
The correct answer is (b) 10.0.
The percentage gain is calculated by dividing the difference between the selling price and the purchasing price by the purchasing price and multiplying by 100. In this case, the selling price is $11 and the purchasing price is $10, so the percentage gain is $\frac{11-10}{10} \times 100 = 10\%$.
Option (a) is incorrect because it is the percentage decrease, not the percentage gain. Option (c) is incorrect because it is the percentage gain if the selling price is $11.10 and the purchasing price is $10. Option (d) is incorrect because it is the percentage gain if the selling price is $11 and the purchasing price is $0.