alleryFind the fourth proportional to $4$, $9$ and $12$.
A$18$
B$21$
C$24$
D$27$
Answer & Solution
Correct answer: D. $27$
If $4 : 9 = 12 : x$, then by the product-of-means equals product-of-extremes rule, $4x = 9 \times 12 = 108$, so $x = 27$.
Keep practising Ratio and Proportion
Browse all Ratio and Proportion questions for AFCAT, or explore more Quantitative Reasoning topics.
Related questions
₹$5400$ is divided among A, B and C in the ratio $3 : 5 : 7$. How much does B receive?Find the compounded ratio of $(2 : 3)$, $(5 : 7)$ and $(4 : 9)$.If $\dfrac{a}{b} = \dfrac{3}{5}$, find the value of $\dfrac{a+b}{a-b}$.Find the mean proportional between $16$ and $25$.Which of the following is equivalent to the ratio $4 : 5$?