A commuter drives to his consulting firm at 30 km/h and arrives 15 minutes late. If he increases his speed to 40 km/h, he arrives 5 minutes early. Find the distance to his firm. MCQ with Answer and Explanation
A commuter drives to his consulting firm at 30 km/h and arrives 15 minutes late. If he increases his speed to 40 km/h, he arrives 5 minutes early. Find the distance to his firm.
A. 40 km
B. 45 km
C. 35 km
D. 50 km
Answer: Option A
Solution (By JKSSB Mock Tests)
Time difference = 15 - (-5) = 20 minutes = 20/60 = 1/3 hours. Let distance be d. d/30 - d/40 = 1/3 => (4d - 3d)/120 = 1/3 => d/120 = 1/3 => d = 40 km.
A man can walk a distance in 4 hours and ride back in 3 hours. If he walks both ways, he takes 8 hours. How much time will he take if he rides both ways?
Explanation:
Let walking time one way be W and riding time one way be R. W + R = 7 hours. Walking both ways: 2W = 8 => W = 4 hours. Substituting W in first equation: 4 + R = 7 => R = 3 hours. Riding both ways: 2R = 2 * 3 = 6 hours.
A person walks from his house to his office at a speed of 4 km/h and reaches 10 minutes late. If he walks at 5 km/h, he reaches 5 minutes early. Find the distance between his house and office.
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