Civil Engineering - UPSC Civil Service Exam Questions - Discussion

2. 

If the efficiencies of BOD removal of first-stage and second-stage trickling filters are each 65.0%, then what is the overall BOD removal efficiency of these filters ?

[A]. 65%
[B]. 77.25%
[C]. 87.75%
[D]. 92.6%

Answer: Option C

Explanation:

No answer description available for this question.

Mayank said: (Jun 26, 2016)  
This can be solved by following this method.

= .65 + .65 * 0.35.

Vicky Vikrant said: (Oct 6, 2016)  
Efficienct = 1 - (1 - n1)(1 - n2) = 1 - (1 - 0.65)(1 - 0.65) = 0.8775 i.e 87.75%.

Lara said: (Jul 8, 2017)  
I think the answer should be C.

Sunil Kumar said: (Jul 12, 2018)  
Yes, C option is correct.

Naresh Kumar Meena said: (May 30, 2020)  
Thanks @Mayank.

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