Home › SSC CGL › Quantitative Aptitude › Ratio and Proportion › Find the fourth proportional to $4$, $9$ and $12$.
Find 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 $x = 27$.
Related questions
Ratio of two numbers is 3 : 5. If x is added to each, the new ratio is 7 : 5. Sum of squarA : B = 1/4 : 1/5 and B : C = 1/8 : 1/7. Find (4A + 2B + 2C) / (3B + C).The ratio of 30 minutes to 40 minutes is written as:S is 7 years younger than R. If the ratio of their ages is 7 : 9, what is S's age?If a 24.6 m long wire is divided in the ratio 12 : 29, what is the length of the longer piA sum of Rupees 110 is made of Rupees 2, Rupees 1 and 50 paise coins in the ratio 1 : 2 : 1200 soldiers in a fort had enough food for 28 days. After 4 days, some soldiers left and In a school, 10% of the boys equal in number to 1/4th of the girls. What is the ratio of b