Question

What number must be added to each of the numbers 7, 11 and 19 so that the resulting numbers may be in continued proportion?

Options

• –4

• –3

• 3

• 4

Answer 1

–3

Explanation:

For continued proportion, (11 + x)² = (7 + x)(19 + x).

Simplifying gives 4x + 12 = 0, so x = −3.