Banking Quantitative Aptitude Sample Paper Quantitative Aptitude Sample Paper-1

A well 20 m in diameter is dug 14m deep and the earth taken out is spread all around it to a width of 5 m to form an embankment. The height of the embankment is

A) 10 m

B) 11 m

C) 11.2 m

D) 11.5 m

Correct Answer: C

Solution :

[c] Radius of the base of well \[=\frac{20}{2}=10\,m\]

Volume of the earth taken out

\[=\pi {{r}^{2}}h=\frac{22}{7}\times {{10}^{2}}\times 14\]

Let the height of embankment be x m.

Here, \[R=15m,\]\[r=10m\]

Then, volume

\[=\pi ({{R}^{2}}-{{r}^{2}})\times x=\frac{22}{7}\times ({{15}^{2}}-{{10}^{2}})\times x\]

\[=\frac{22}{7}\times 25\times 5\times x\]

Clearly, \[\frac{22}{7}\times 25\times 5\times x=\frac{22}{7}\times {{10}^{2}}\times 14\]

\[\Rightarrow \] \[x=\frac{100\times 14}{25\times 5}=11.2\,\,m\]