A vehicle covers a lap distance of 450 km at a uniform speed. If its velocity is cut by 15 km/h, the trip maps 1.5 hours longer. Find the original speed. MCQ with Answer and Explanation

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A vehicle covers a lap distance of 450 km at a uniform speed. If its velocity is cut by 15 km/h, the trip maps 1.5 hours longer. Find the original speed.

A. 60 km/h

B. 75 km/h

C. 80 km/h

D. 90 km/h

Answer: Option B

Solution (By JKExamLibrary)

Let original speed be s. 450/(s-15) - 450/s = 1.5 => 300/(s-15) - 300/s = 1 => 300(15) = s(s-15) => 4500 = s(s-15). Solving s^2 - 15s - 4500 = 0 gives (s-75)(s+60) = 0. Baseline speed = 75 km/h.

This question belongs to: Maths Time Speed and Distance

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Practice More Time Speed and Distance Questions

Question #1 Report Error

Two points M and N are separated by 300 km. At 8:00 AM, a car leaves M for N at 60 km/h. At 9:00 AM, another car leaves N for M at 90 km/h. At what time will they pass each other?

A. 10:40 AM

B. 10:36 AM

C. 10:24 AM

D. 10:48 AM

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Correct Answer: Option B

Explanation:
By 9:00 AM, the first car covers 60 km * 1 hour = 60 km. The remaining distance between them is 300 - 60 = 240 km. Relative speed = 60 + 90 = 150 km/h. Time to meet after 9:00 AM = 240 / 150 = 8/5 hours = 1 hour 36 minutes. Meeting time = 9:00 AM + 1 hour 36 minutes = 10:36 AM.

This question belongs to: Maths Time Speed and Distance

Question #2 Report Error

A motorboat rows 24 km downstream in 3 hours and tracks the identical route upstream back to the jetty point in 4 hours. Find the net speed index of the current stream flow.

A. 1.2 km/h

B. 0.8 km/h

C. 1.5 km/h

D. 1.0 km/h

View Answer & Solution Discuss

Correct Answer: Option D

Explanation:
Downstream speed = 24 / 3 = 8 km/h. Upstream speed = 24 / 4 = 6 km/h. Speed of current stream flow = (8 - 6) / 2 = 2 / 2 = 1.0 km/h.

This question belongs to: Maths Time Speed and Distance