TGPSC HMWSSB Manager 2015 Paper 2 · Question 50
Question 50 of the TSPSC Manager (Engineering), HMWSSB, 2015: Paper 2 (Civil Engineering) (1 November 2015). Try it first, then open the answer and explanation.
In a catchment there are six rain gauge stations with average depth of rainfall of 92.8cm and standard deviation of the rainfall is recorded in these rain gauge stations is 30.7cm. For a 10% degree of error in the measurement of mean rainfall, the optimum number of stations required is
- 5 nos
- 6 nos
- 10 nos
- 11 nos
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Answer: (4) 11 nos
Coefficient of variation C_v = 100 × 30.7/92.8 = 33.08%. Optimum number of stations N = (C_v/ε)² = (33.08/10)² = 10.9, which is rounded up to 11 stations.