Question
A boy goes to his school from his house at a speed of 3 km/hr and returns at a speed of 2 km/ hr. If he takes 5 hours in going and coming, the distance between his house and school is :
Answer: Option D
Answer: (d)Let the required distance be x km. Then,$x/3 + x/2$ = 5${2x + 3x}/6$ = 55x = 6 × 5x = ${6 × 5}/5$ = 6 kmUsing Rule 5,Here, x = 3, y = 2Average Speed = ${2 × x × y}/{x + y}$= ${2 × 3 × 2}/{3 + 2} = 12/5$ km/hrTotal distance = $12/5 × 5$ = 12kmRequired distance = $12/2$ = 6 km
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Answer: (d)Let the required distance be x km. Then,$x/3 + x/2$ = 5${2x + 3x}/6$ = 55x = 6 × 5x = ${6 × 5}/5$ = 6 kmUsing Rule 5,Here, x = 3, y = 2Average Speed = ${2 × x × y}/{x + y}$= ${2 × 3 × 2}/{3 + 2} = 12/5$ km/hrTotal distance = $12/5 × 5$ = 12kmRequired distance = $12/2$ = 6 km
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