If the third proportion of two numbers is 27 and the first number is 12, then find the 2nd number.
1). 16
2). 18
3). 14
4). 20
To find the third proportion we use a formula b² = ac where a and b are two numbers and c is the third proportion of them.
⇒ b² = ac
⇒ b² = 27 × 12
∴ b = 18