Abhay takes 2 hours more than Sameer to cover 30 km. If Abhay doubles his speed, he would take 1 hour less than Sameer. What is Abhay's speed (km/h)?
Aptitude
Time and Distance
Difficulty: Medium
Choose an option
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A5 km/h
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B6 km/h
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C7.5 km/h
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D4 km/h
Answer
Correct Answer: 5 km/h
Explanation
Translate the time statements into equations using Time = Distance / Speed.
Step-by-step calculationLet Abhay’s speed = a and Sameer’s speed = s (km/h).30 / a = 30 / s + 2 …(1)30 / (2a) = 30 / s − 1 …(2)Subtract (2) from (1):30/a − 30/(2a) = (30/s + 2) − (30/s − 1)15/a = 3a = 5 km/h
VerificationAbhay time = 30 / 5 = 6 hFrom (1): 6 = 30/s + 2 ⇒ 30/s = 4 ⇒ s = 7.5 km/hIf Abhay doubles speed to 10 km/h: time = 30/10 = 3 h, which is 1 h less than Sameer’s 4 h (matches)
Common pitfallsBe careful with “2 hours more” vs “1 hour less” and ensure you attach them to the correct person’s time.
Final Answer5 km/h