Question

If y is inversely proportional to x, and y = 400 when x = 20, what is the value of y when x = 40 and x = 80?

A
400 and 100


B
200 and 100


C
250 and 480


D
500 and 200

Answer 1

The correct answer is B. 200 and 100. When y is inversely proportional to x, it means that the ratio of x to y remains constant. In this case, when x = 20, y = 400, which means that the ratio of x to y is 20/400. Since the ratio is constant, we can use that ratio to find the values of y when x = 40 and x = 80. When x = 40, y = (20/400) x 40 = 200 and when x = 80, y = (20/400) x 80 = 100.