Discussion
A well with an inner diameter of 14 meters is dug to a depth of 15 meters. The excavated earth is spread evenly around the well to a width of 7 meters, forming an embankment. The height of the embankment is :
Answer: B
The embankment is 5 meter high.
The earth dug out is a cylinder of radius 7 m and depth 15 m. It is spread as a ring from radius 7 m to radius 7 + 7 = 14 m, so its volume equals the area of that ring times the height \(h\):
\[ \begin{aligned} \pi (7^{2})(15) &= \pi (14^{2} - 7^{2}) h \\ 735 &= 147h \\ h &= 5 \text{ m} \end{aligned} \]
Using the full circle of radius 14 m instead of the ring would give \(735/196 = 3.75\) m, which is not offered; the well itself is not covered by the embankment.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development