2 Views

Question : The ratio of the total surface areas of the two cubes is 49 : 81. What is the ratio of their volumes?

Option 1: 343 : 729

Option 2: 294 : 486

Option 3: 7 : 9

Option 4: 49 : 121


Team Careers360 9th Jan, 2024
Answer (1)
Team Careers360 17th Jan, 2024

Correct Answer: 343 : 729


Solution : Given: The ratio of the total surface areas of the two cubes is 49 : 81.
The volume of the cube = $x^3$,
The total surface area of the cube = $6x^2$
where $x$ is the side of the cube.
Let the sides of the cubes be $y$ and $z$, respectively.
According to the question,
$\frac{6y^2}{6z^2}=\frac{49}{81}$
⇒ $\frac{6y^2}{6z^2}=\frac{49}{81}$
⇒ $\frac{y}{z}=\frac{7}{9}$
Let $y=7k$ and $z=9k$
The ratio of their volumes $=\frac{y^3}{z^3}=\frac{7k^3}{9k^3}=\frac{343}{729}=343: 729$
Hence, the correct answer is 343 : 729.

Know More About

Related Questions

TOEFL ® Registrations 2024
Apply
Accepted by more than 11,000 universities in over 150 countries worldwide
Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
GRE ® Registrations 2024
Apply
Apply for GRE® Test now & save 10% with ApplyShop Gift Card | World's most used Admission Test for Graduate & Professional Schools
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books