What is the third proportional to 9 and 12?

Third Proportional to 9 and 12

Formula to find the third promotional:

• If a, b, and c are in proportion ⇒ a/b = b/c ⇒ b² = ac

Calculation: Let the third proportional to 9 and 12 be x

According to the question, 9 : 12 :: 12 : x

⇒ 9/12 = 12/x

⇒ x = (12 × 12)/9

⇒ x = 16

∴ The third proportional to 9 and 12 is 16.

Summary:

What is the third proportional to 9 and 12? (a) 19 (b) 16 (c) 18 (d) 17

16 is the third proportional to 9 and 12. The formula and the step=by-step process to calculate the third proportional has been explained in this post above.