Find the fourth proportional to the numbers 18, 27 and 34.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 51
The fourth proportional to \(a,\ b,\ c\) is the number \(d\) with \(a:b=c:d\), so \(\displaystyle d=\frac{b\times c}{a}\).
\(18:27=34:d\)
\(\displaystyle d=\frac{27\times34}{18}=\frac{918}{18}=51\)
The fourth proportional is 51.