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A motorist travels to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/ hr. His average speed for the whole journey in km/hr is-
Answer & Solution
Correct Answer:
Option
C
Average speed
$$\eqalign{ & = \left( {\frac{{2xy}}{{x + y}}} \right){\text{ km/hr}} \cr & = \left( {\frac{{2 \times 50 \times 30}}{{50 + 30}}} \right){\text{ km/hr}} \cr & = 37.5{\text{ km/hr}} \cr} $$
$$\eqalign{ & = \left( {\frac{{2xy}}{{x + y}}} \right){\text{ km/hr}} \cr & = \left( {\frac{{2 \times 50 \times 30}}{{50 + 30}}} \right){\text{ km/hr}} \cr & = 37.5{\text{ km/hr}} \cr} $$
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