Civil Engineering - Water Resources Engineering - Discussion

22. 

The respective storm totals at three surrounding stations A, B and C are 110, 90 and 70 mm. If the normal annual precipitation amounts at stations X, A, B and C are respectively 1000, 1100, 1200 and 1250 mm, the estimated storm precipitation at X is

[A]. 75 mm
[B]. 77 mm
[C]. 79 mm
[D]. 81 mm.

Answer: Option B

Explanation:

No answer description available for this question.

Ahdj said: (Dec 24, 2015)  
Any one please explain me how answer 77 mm right answer?

Vinay said: (Jan 14, 2016)  
Precipitation at X = Nx/m [P1/N1+P2/N2+....+Pm/Nm].

M = Number of stations minus 1.

Hence,

Px = 1000/(4-1) [110/1100+90/1200+70/18] = 77.

Ghost said: (Nov 15, 2017)  
Precipitation at X = Nx/m [P1/N1+P2/N2+....+Pm/Nm].

M = Number of stations. - 1(4-1=3).

Px = 1000/(4-1) [110/1100+90/1200+70/1250] = 77.

Akshay said: (Jun 6, 2018)  
There are 2 methods.

1)Arithmetic.
2)Normal Ratio.

1)Arithmetic:
Take 10% of the missing storm means for x.
(1000*(10/100))=100,
Add 1000+100=1100,
now subtract 10% from 1000,
1000-100=900,
The normal annual rainfall for B & C are beyond values 900 and 1100.

So second method should be used,
2)Normal ratio method:
x=1/3{ [1000*(110/1100)]+[1000*(90/1200)]+[1000*(70/1250)]},
x=77mm.

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