53 Views

Question : A well with an inner radius of 3 m, is dug 6 m deep. The soil taken out of it has been spread evenly all around it to a width of 2 m to form an embankment. The height (in m) of the embankment is:

Option 1: $4 \frac{1}{2}$

Option 2: $4 \frac{1}{4}$

Option 3: $3 \frac{1}{4}$

Option 4: $3 \frac{3}{8}$


Team Careers360 5th Jan, 2024
Answer (1)
Team Careers360 8th Jan, 2024

Correct Answer: $3 \frac{3}{8}$


Solution : The volume of the well (a cylinder) is $\pi r^2 h$, where $r$ is the radius and $h$ is the height. 
Substituting r = 3 m and h = 6 m.
The volume of the well = $\pi r^2 h= \pi \times 3^2 \times 6 =54\pi \;m^3$
The embankment is in the shape of a hollow cylinder with an outer radius, R = r + width = 3 + 2 = 5 m and an inner radius r = 3 m.
Let the height of the embankment be $h_2$.
The volume of the embankment = $\pi (R^2 - r^2) h_2$
Equating the volume of the well and the embankment,
$⇒54\pi = \pi (5^2 - 3^2) h_2$
Solving for $h_2$, 
$⇒h_2 = \frac{54}{16} = \frac{27}{8} = 3\frac{3}{8}\;m$
Hence, the correct answer is $3\frac{3}{8}$.

SSC CGL Complete Guide

Candidates can download this ebook to know all about SSC CGL.

Download EBook

Know More About

Related Questions

Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
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