Question

The mean proportion between x and y is 6. The third proportional to x and y is 48. Then x : y equals ______.

Options

• 1 : 3

• 1 : 4

• 1 : 6

• 1 : 9

Answer 1

The mean proportion between x and y is 6. The third proportional to x and y is 48. Then x : y equals 1 : 4.

Explanation:

The mean proportion gives xy = 36, while the third proportional gives `y^2/x = 48`. Solving these yields x = 3 and y = 12, so x : y = 1 : 4.