Question

A vehicle when climbing up a gradient consumes petrol at the rate of 1 litre per 8 kms, while coming down it gives 12 kms per litre. Find its average consumption for to and fro travel between two places situated at the two ends of a 25kms long gradient.

A 80 Correct Answer Incorrect Answer
B 25 Correct Answer Incorrect Answer
C 9.6 Correct Answer Incorrect Answer
D 3.2 Correct Answer Incorrect Answer
E 15 Correct Answer Incorrect Answer

Solution

X (km/L)                W(km)           `(w/x)-> (l)` 8                              25                   `25/8 = 3.125` ` 12                            25                  `25/12 = 2.083`                         `sum` wi= 50          `sum (Wi)/(chiiota ) = 5.208` Harmonic Mean =  `(sum wi)/(sum(wi)/(chiiota))`                                 = `(50)/(5.208)`                                = 9.6 liter  Hence average consumption is 9.6 Liters.

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