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A man covers three equal distances at 10 km/h, 20 km/h and 60 km/h. What is his average speed for the whole journey? Answer: B. 18 km/h Answer: (B) 18 km/h Take each distance = 60 km (LCM). Times = 6 h + 3 h + 1 h = 10 h for 180 km. Average speed = 180 ÷ 10... Time, speed and distance 1 answer
If a person walks at 15 km/h instead of 12 km/h, he would walk 18 km more in the same time. What distance did he actually walk? Answer: B. 72 km Answer: (B) 72 km The extra 3 km/h gives 18 km more, so the time = 18 ÷ 3 = 6 h. Actual distance = 12 × 6 = 72 km. Trap: 90... Time, speed and distance 1 answer
A car goes from P to Q at 60 km/h and returns at 40 km/h. The whole trip takes 5 hours. What is the distance from P to Q? Answer: C. 120 km Answer: (C) 120 km Average speed = 2 × 60 × 40/100 = 48 km/h. Total distance = 48 × 5 = 240 km. One way = 240 ÷ 2 = 120 km... Time, speed and distance 1 answer
A train running at 90 km/h passes a man walking at 6 km/h in the same direction in 12 seconds. What is the length of the train? Answer: A. 280 m Answer: (A) 280 m Relative speed = 90 − 6 = 84 km/h = 70/3 m/s. Length = 70/3 × 12 = 280 m. Time, speed and distance 1 answer
In a 1 km race, A beats B by 40 m or by 8 seconds. How long does A take to run the race? Answer: C. 192 seconds Answer: (C) 192 seconds B runs the last 40 m in 8 s, so B's speed = 5 m/s and B's time = 1000 ÷ 5 = 200 s. A finishes... Time, speed and distance 1 answer
Two runners start together from the same point on a 600 m circular track and run in the same direction at 4 m/s and 6 m/s. After how long will they first meet again? Answer: B. 300 seconds Answer: (B) 300 seconds The faster runner must gain one full lap (600 m) at a relative speed of 2 m/s. Time = 600 ÷ 2... Time, speed and distance 1 answer
A train is running 20 minutes late. By increasing its speed by 16 km/h it covers the next 160 km and arrives on time. What is its usual speed? Answer: A. 80 km/h Answer: (A) 80 km/h 160/v - 160/v + 16 = 1/3 , so v(v + 16) = 160 × 16 × 3 = 7680. 80 × 96 = 7680, so v = 80 km/h. (Check... Time, speed and distance 1 answer
Stations A and B are 190 km apart. A train leaves A at 6 a.m. towards B at 30 km/h. Another train leaves B at 7 a.m. towards A at 50 km/h. At what time do they meet? Answer: C. 9 a.m. Answer: (C) 9 a.m. By 7 a.m. the first train has covered 30 km, leaving a gap of 160 km. From 7 a.m. they close the gap at... Time, speed and distance 1 answer
A train passes two men walking in the same direction as the train at 3 km/h and 5 km/h in 10 seconds and 11 seconds respectively. What is the speed of the train? Answer: A. 25 km/h Answer: (A) 25 km/h The train's length is the same both times: (v − 3) × 10 = (v − 5) × 11 (the 5/18 factor cancels). 10v... Time, speed and distance 1 answer
Without stoppages a bus runs at 64 km/h; including stoppages its average speed is 48 km/h. For how many minutes per hour does the bus stop? Answer: D. 15 minutes Answer: (D) 15 minutes In one hour the bus loses 64 − 48 = 16 km of running. At 64 km/h that takes 16/64 × 60 = 15 min... Time, speed and distance 1 answer
Two trains start at the same time from P and Q towards each other. After meeting, they take 4 hours and 9 hours respectively to reach their destinations. If the train from P runs at 60 km/h, what is the speed of the train from Q? Answer: A. 40 km/h Answer: (A) 40 km/h Shortcut: S_P/S_Q = √(t_Q/t_P) = √(9/4) = 3/2 . S_Q = 60 × 2/3 = 40 km/h. Trap: 90 km/h inverts the r... Time, speed and distance 1 answer
15 men can finish a job in 20 days. How many days will 25 men take to finish the same job? Answer: D. 12 days Answer: (D) 12 days Shortcut: M₁D₁ = M₂D₂. 15 × 20 = 25 × D, so D = 12 days. Time and work 1 answer
A can finish a piece of work in 12 days and B in 18 days. How many days will they take working together? Answer: D. 7.2 days Answer: (D) 7.2 days Shortcut: together = ab/a+b = 12 × 18/30 = 7.2 days. LCM method: work = 36 units; A does 3/day, B 2... Time and work 1 answer
A can do a piece of work in 10 days. What fraction of the work is left after A works for 4 days? Answer: A. 3/5 Answer: (A) 3/5 A does 1/10 per day, so 4/10 in 4 days. Work left = 1 - 2/5 = 3/5 . Time and work 1 answer
A and B together can do a work in 8 days. A alone can do it in 12 days. How many days will B alone take? Answer: A. 24 days Answer: (A) 24 days Shortcut: B = 8 × 12/12 - 8 = 96/4 = 24 days. LCM: work = 24 units; A+B = 3/day, A = 2/day, so B = 1/... Time and work 1 answer
A is twice as efficient as B. Together they finish a work in 14 days. How many days will A alone take? Answer: D. 21 days Answer: (D) 21 days Efficiencies A : B = 2 : 1. Total work = (2 + 1) × 14 = 42 units. A alone = 42 ÷ 2 = 21 days. Time and work 1 answer
A can do a work in 20 days and B in 30 days. They work together for 6 days. What fraction of the work is left? Answer: B. 1/2 Answer: (B) 1/2 Together per day = 1/20 + 1/30 = 1/12 . In 6 days they do 6/12 = 1/2 . Work left = 1/2 . Time and work 1 answer
A is 25% more efficient than B. If B takes 20 days to do a work, how many days will A take? Answer: A. 16 days Answer: (A) 16 days Time is inversely proportional to efficiency. A's time = 20 ÷ 1.25 = 16 days. Trap: 25% less time (15... Time and work 1 answer
A, B and C can finish a work in 10, 12 and 15 days respectively. How many days will they take working together? Answer: C. 4 days Answer: (C) 4 days LCM method: work = 60 units. A = 6, B = 5, C = 4 units/day; together 15 units/day. Days = 60 ÷ 15 = 4. Time and work 1 answer
A and B together can do a work in 10 days, B and C in 15 days, and C and A in 12 days. How many days will A, B and C take working together? Answer: B. 8 days Answer: (B) 8 days Work = 60 units. (A+B) = 6, (B+C) = 4, (C+A) = 5 units/day. Adding: 2(A+B+C) = 15, so A+B+C = 7.5 units... Time and work 1 answer
A can do a work in 15 days. B is 50% more efficient than A. How many days will they take working together? Answer: A. 6 days Answer: (A) 6 days B takes 15 ÷ 1.5 = 10 days. Together = 15 × 10/25 = 6 days. Efficiency method: A : B = 2 : 3, work = 2... Time and work 1 answer
4 men or 6 women can finish a work in 12 days. How many days will 3 men and 3 women take to finish it? Answer: C. 9.6 days Answer: (C) 9.6 days 4 men = 6 women, so 1 woman = 2/3 man. 3 men + 3 women = 3 + 2 = 5 men. 4 men take 12 days, so 5 me... Time and work 1 answer
12 men working 8 hours a day finish a job in 10 days. In how many days will 15 men working 6 hours a day finish it? Answer: A. 102/3 days Answer: (A) 102/3 days Shortcut: M₁D₁H₁ = M₂D₂H₂. 12 × 10 × 8 = 15 × D × 6, so D = 960/90 = 102/3 days. Time and work 1 answer
A can do a work in 20 days and B in 30 days. They start together, but A leaves after 5 days. In how many days in all is the work finished? Answer: A. 22.5 days Answer: (A) 22.5 days Work = 60 units; A = 3, B = 2 units/day. In 5 days together they do 25 units; 35 units remain. B... Time and work 1 answer

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