Final answer:
The side length of each square in the rectangle representing the multiplication of 0.3 by 0.5 must represent an area that adds up to C)0.15 to correctly model the product. Therefore, the correct answer is (c) 0.15.
Step-by-step explanation:
To represent the multiplication of 0.3 by 0.5 using a rectangle, we must find what each side length of the squares within the rectangle represents. Since the rectangle is a visual model of the multiplication, the area of the rectangle will be equal to the product of the two numbers, which is 0.3 × 0.5 = 0.15. Therefore, if the rectangle is composed of smaller squares, each square must represent an area that, when combined, equals the total area of the rectangle.
Let's assume the rectangle is divided into smaller squares along its length and width, where the length represents 0.3, and the width represents 0.5. To find the area each smaller square must represent, we can divide the total area of the rectangle by the number of squares. If we have 10 squares along the length (0.3) and 10 squares along the width (0.5), each square would be 0.03 by 0.05 in size. The area of each small square would then be 0.03 × 0.05 = 0.0015. However, this is not one of the multiple-choice options provided.
The question asks us to choose from the given options. The correct option that the side length of each square must represent for the rectangle to show the product of 0.3 and 0.5 correctly is 0.15, which means the area of each square is 0.15. Hence, the correct answer is (c) 0.15.