Aptitude  Volume and Surface Area  Discussion
Discussion Forum : Volume and Surface Area  General Questions (Q.No. 5)
5.
A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm^{3}, then the weight of the pipe is:
Answer: Option
Explanation:
External radius = 4 cm,
Internal radius = 3 cm.
Volume of iron 




= 462 cm^{3}. 
Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.
Discussion:
60 comments Page 1 of 6.
Anupam Tripathi said:
1 decade ago
Why internal radius is 3 cm?
Neelam shelke said:
1 decade ago
Thickness of the pipe is 1cm, and external radius is 4cm, so 41=3, thus the internal radius is 3, as per my thinking.
Divya said:
1 decade ago
Why [4]^2[3]^2 while calculating volume?
Mobi001 said:
1 decade ago
If the thickness of pipe is 1 cm the internal diameter should not be 7 cm if yes then internal radius must be 3.5 ?
Mobi001 said:
1 decade ago
Thats fine. I understood the logic.
Because from both side the 1cm will be deducted.
Because from both side the 1cm will be deducted.
Krishna said:
1 decade ago
Why external radius is 4cm how is it ?
Sandeep said:
1 decade ago
Because external diameter is 8cm then.
External radius is 8/2=4cm.
External radius is 8/2=4cm.
Anju said:
1 decade ago
Why internal radius is 3?
Manojit said:
1 decade ago
As the thickness of the pipe is 1 cm.....
Gopal said:
1 decade ago
How to convert gm to kg ?
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers