GATE 2020 AG – Question 19
Mean annual rainfall at A,B,C,D,E is 1020,810,675,940,780 mm. During a year with A unavailable, B,C,D,E record 890,725,980,850 mm. Estimate rainfall at A in mm.
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Correct answer: (D) 1098
Explanation
The station normals differ appreciably, so use the normal-ratio method: $P_A=(1020/4)(890/810+725/675+980/940+850/780)=1097.9$ mm. Rounding gives 1098 mm, D. A simple arithmetic average would ignore the different long-term station climates.