PlacementPrepA car goes from P to Q at 80 km/h and returns at 40 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 80 × 40 / 120 = 53 1/3 km/h.
Answer: (B) 53 1/3 km/h
Quantitative Aptitude · Work and motion
Time, Speed and Distance: placement practice questions
30 moderate questions in the pattern of campus placement tests. Pick an option to check your answer, then open the step-by-step solution.
Driving at 60 km/h, a man reaches his office 10 minutes late. Driving at 75 km/h, he reaches on time. How far is his office?
Solution
d/60 − d/75 = 10/60.
d × (15)/(60 × 75) = 1/6, so d = 50 km.
Answer: (B) 50 km
A car moves at 108 km/h. How many metres does it cover in 12 seconds?
Solution
108 km/h = 108 × 5/18 = 30 m/s.
Distance = 30 × 12 = 360 m.
Answer: (B) 360 m
A thief leaves a town at 50 km/h. 3 hours later, a police car follows at 60 km/h. How long after starting will the police catch the thief?
Solution
Head start = 50 × 3 = 150 km.
Relative speed = 60 − 50 = 10 km/h, so time = 150/10 = 15 hours.
Answer: (D) 15 hours
A car moves at 72 km/h. How many metres does it cover in 26 seconds?
Solution
72 km/h = 72 × 5/18 = 20 m/s.
Distance = 20 × 26 = 520 m.
Answer: (C) 520 m
Two towns are 150 km apart. Two cars start from them at the same time towards each other at 35 km/h and 40 km/h. After how long will they meet?
Solution
Relative speed = 35 + 40 = 75 km/h.
Time = 150/75 = 2 hours.
Answer: (D) 2 hours
By walking at 2/3 of his usual speed, a man is 40 minutes late. What is his usual time for the journey?
Solution
At 2/3 of the speed, time becomes 3/2 of the usual time T.
3T/2 − T = 40, so T × 1/2 = 40 and T = 80 minutes.
Answer: (A) 80 minutes
Driving at 45 km/h, a man reaches his office 15 minutes late. Driving at 60 km/h, he reaches on time. How far is his office?
Solution
d/45 − d/60 = 15/60.
d × (15)/(45 × 60) = 0.25, so d = 45 km.
Answer: (C) 45 km
A car moves at 90 km/h. How many metres does it cover in 59 seconds?
Solution
90 km/h = 90 × 5/18 = 25 m/s.
Distance = 25 × 59 = 1475 m.
Answer: (D) 1475 m
A car goes from P to Q at 36 km/h and returns at 45 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 36 × 45 / 81 = 40 km/h.
Answer: (C) 40 km/h
A car moves at 72 km/h. How many metres does it cover in 57 seconds?
Solution
72 km/h = 72 × 5/18 = 20 m/s.
Distance = 20 × 57 = 1140 m.
Answer: (A) 1140 m
A thief leaves a town at 40 km/h. 3 hours later, a police car follows at 60 km/h. How long after starting will the police catch the thief?
Solution
Head start = 40 × 3 = 120 km.
Relative speed = 60 − 40 = 20 km/h, so time = 120/20 = 6 hours.
Answer: (C) 6 hours
Driving at 30 km/h, a man reaches his office 24 minutes late. Driving at 40 km/h, he reaches on time. How far is his office?
Solution
d/30 − d/40 = 24/60.
d × (10)/(30 × 40) = 0.4, so d = 48 km.
Answer: (C) 48 km
A car moves at 72 km/h. How many metres does it cover in 20 seconds?
Solution
72 km/h = 72 × 5/18 = 20 m/s.
Distance = 20 × 20 = 400 m.
Answer: (D) 400 m
A thief leaves a town at 30 km/h. 3 hours later, a police car follows at 40 km/h. How long after starting will the police catch the thief?
Solution
Head start = 30 × 3 = 90 km.
Relative speed = 40 − 30 = 10 km/h, so time = 90/10 = 9 hours.
Answer: (D) 9 hours
A car goes from P to Q at 50 km/h and returns at 30 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 50 × 30 / 80 = 37.5 km/h.
Answer: (B) 37.5 km/h
A car moves at 108 km/h. How many metres does it cover in 35 seconds?
Solution
108 km/h = 108 × 5/18 = 30 m/s.
Distance = 30 × 35 = 1050 m.
Answer: (B) 1050 m
By walking at 3/4 of his usual speed, a man is 20 minutes late. What is his usual time for the journey?
Solution
At 3/4 of the speed, time becomes 4/3 of the usual time T.
4T/3 − T = 20, so T × 1/3 = 20 and T = 60 minutes.
Answer: (D) 60 minutes
A thief leaves a town at 45 km/h. 3 hours later, a police car follows at 60 km/h. How long after starting will the police catch the thief?
Solution
Head start = 45 × 3 = 135 km.
Relative speed = 60 − 45 = 15 km/h, so time = 135/15 = 9 hours.
Answer: (A) 9 hours
A car goes from P to Q at 80 km/h and returns at 20 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 80 × 20 / 100 = 32 km/h.
Answer: (A) 32 km/h
Two towns are 240 km apart. Two cars start from them at the same time towards each other at 40 km/h and 20 km/h. After how long will they meet?
Solution
Relative speed = 40 + 20 = 60 km/h.
Time = 240/60 = 4 hours.
Answer: (D) 4 hours
A car goes from P to Q at 60 km/h and returns at 48 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 60 × 48 / 108 = 53 1/3 km/h.
Answer: (A) 53 1/3 km/h
By walking at 4/6 of his usual speed, a man is 20 minutes late. What is his usual time for the journey?
Solution
At 4/6 of the speed, time becomes 6/4 of the usual time T.
6T/4 − T = 20, so T × 2/4 = 20 and T = 40 minutes.
Answer: (B) 40 minutes
A thief leaves a town at 40 km/h. 1 hour later, a police car follows at 60 km/h. How long after starting will the police catch the thief?
Solution
Head start = 40 × 1 = 40 km.
Relative speed = 60 − 40 = 20 km/h, so time = 40/20 = 2 hours.
Answer: (B) 2 hours
A car goes from P to Q at 20 km/h and returns at 80 km/h. What is its average speed for the round trip?
Solution
For equal distances, average speed = 2ab/(a + b) = 2 × 20 × 80 / 100 = 32 km/h.
Answer: (B) 32 km/h
Driving at 45 km/h, a man reaches his office 10 minutes late. Driving at 60 km/h, he reaches on time. How far is his office?
Solution
d/45 − d/60 = 10/60.
d × (15)/(45 × 60) = 1/6, so d = 30 km.
Answer: (C) 30 km
Two towns are 150 km apart. Two cars start from them at the same time towards each other at 40 km/h and 20 km/h. After how long will they meet?
Solution
Relative speed = 40 + 20 = 60 km/h.
Time = 150/60 = 2.5 hours.
Answer: (D) 2.5 hours
By walking at 4/6 of his usual speed, a man is 60 minutes late. What is his usual time for the journey?
Solution
At 4/6 of the speed, time becomes 6/4 of the usual time T.
6T/4 − T = 60, so T × 2/4 = 60 and T = 120 minutes.
Answer: (D) 120 minutes
A thief leaves a town at 40 km/h. 3 hours later, a police car follows at 50 km/h. How long after starting will the police catch the thief?
Solution
Head start = 40 × 3 = 120 km.
Relative speed = 50 − 40 = 10 km/h, so time = 120/10 = 12 hours.
Answer: (C) 12 hours
Driving at 30 km/h, a man reaches his office 12 minutes late. Driving at 40 km/h, he reaches on time. How far is his office?
Solution
d/30 − d/40 = 12/60.
d × (10)/(30 × 40) = 0.2, so d = 24 km.
Answer: (B) 24 km
Want guided preparation? Placement Papers Prep courses by Dr. Kiran Derle, with video lessons and full-length mocks.
See placement courses ↗