Time, Speed and Distance Questions

Multiple choice
  1. 350 km

  2. 450 km

  3. 400 km

  4. 300 km

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let total distance = 2d km. Time for first half = d/40 hours, second half = d/50 hours. Total time = d/40 + d/50 = d(1/40 + 1/50) = d(5/200 + 4/200) = 9d/200 = 9 hours. Solving: 9d = 1800, d = 200 km. Total distance = 2d = 400 km.

Multiple choice
  1. 6

  2. 4.5

  3. 5

  4. 7.5

  5. None of these इनमें से कोई नहीं

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let boat speed in still water be b and stream speed be c. Downstream speed = b + c, upstream = b - c. First condition: 7.2/(b+c) + 3.2/(b-c) = 2 hours. Second condition (24 min = 0.4 hours): 1.5/(b+c) + 0.6/(b-c) = 0.4. Multiply second by 4: 6/(b+c) + 2.4/(b-c) = 1.6. Notice this is close to the first equation. Subtract: (7.2-6)/(b+c) + (3.2-2.4)/(b-c) = 2-1.6, so 1.2/(b+c) + 0.8/(b-c) = 0.4. Multiply by 5: 6/(b+c) + 4/(b-c) = 2. From original second equation (×10): 15/(b+c) + 6/(b-c) = 4. Solve: Let x = 1/(b+c), y = 1/(b-c). We have 15x + 6y = 4 and 6x + 4y = 2. From second: 3x + 2y = 1, so y = (1-3x)/2. Substituting: 15x + 6(1-3x)/2 = 4, so 15x + 3 - 9x = 4, giving 6x = 1, x = 1/6. Therefore b + c = 6 km/h. Option B (4.5) would be if we miscalculated the relationship.

Multiple choice
  1. 7/4 km/hour

  2. 4/7 km/hour

  3. 21/4 km/hour

  4. 4/21 km/hour

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Downstream: Distance = 84 km, Time = 12 hours, so downstream speed = 84/12 = 7 km/h = (b + c) where b is boat speed and c is current speed. Upstream: Distance = 42 km (half of 84), Time = 12 hours, so upstream speed = 42/12 = 3.5 km/h = (b - c). Subtracting: (b + c) - (b - c) = 7 - 3.5, so 2c = 3.5, giving c = 1.75 km/h = 7/4 km/h.

Multiple choice
  1. 10 km

  2. 12 km

  3. 15 km

  4. 8 km

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total time = 2 hr 40 min = 160 min. Rest = 24 min, so travel time = 136 min. First 40% at 1.25 m/s = 75 m/min, remaining 60% at 5/3 m/s = 100 m/min. Let distance be D. Time = 0.4D/75 + 0.6D/100 = 136. Solving: D(0.4/75 + 0.6/100) = 136, D(0.00533 + 0.006) = 136, D(0.01133) = 136, D = 12000 m = 12 km. Option A is calculation error, C from wrong speed conversion, D from subtracting instead of adding.

Multiple choice
  1. 45 km

  2. 65 km

  3. 72 km

  4. 55 km

  5. 56 km

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let original speed be v km/hr. Distance = v × 40 km. Reduced speed = v - v/13 = 12v/13 km/hr. Distance at reduced speed = (12v/13) × 40 = 480v/13 km. Difference: 40v - 480v/13 = (520v - 480v)/13 = 40v/13 = 5 km. So v = (5 × 13)/40 = 65/40 = 13/8 km/hr. Original distance = (13/8) × 40 = 65 km.

Multiple choice
  1. 2 km/hr

  2. 5 km/hr

  3. 3 km/hr

  4. 8 km/hr

  5. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let boat speed in still water = b = 9 km/hr, current speed = c. Downstream speed = b+c, upstream speed = b-c. Time upstream = 2 × time downstream. Distance upstream = distance downstream (let it be d). So d/(b-c) = 2d/(b+c). Cross-multiplying: d(b+c) = 2d(b-c). b+c = 2b-2c. 3c = b. Therefore current speed c = 9/3 = 3 km/hr. This matches option C.

Multiple choice
  1. 5

  2. 8

  3. 10

  4. 6

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Relative speed = 75 + 85 = 160 km/hr. In 3 minutes (3/60 = 1/20 hour), distance covered = 160 × 1/20 = 8 km. This is the distance between trains 3 minutes before meeting, regardless of starting distance. The trick is recognizing that the distance covered in 3 minutes IS the gap.

Multiple choice
  1. 140 km

  2. 150 km

  3. 142.5 km

  4. 160 km

  5. None of these

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let original speed = s km/h. Distance = s × 21.75. Reduced speed = (14/15)s, distance in same time = (14/15)s × 21.75. Difference = s × 21.75 - (14/15)s × 21.75 = s × 21.75 × (1/15) = 10 km. So s × 1.45 = 10, giving s = 50/7. Total distance = (50/7) × 21.75 = 50 × 3.09 = 154.5, which rounds to approximately 150 km.

Multiple choice
  1. 12 km/hr , 126 km

  2. 21 km/hr , 64 km

  3. 18 km/hr , 21 km

  4. 25 km/hr , 125 km

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let actual speed be v km/h and distance be d km. When speed increases to (v+3), time saved is 10 minutes: d/(v+3) = d/v - 10/60. When speed decreases to (v-4), time lost is 20 minutes: d/(v-4) = d/v + 20/60. Solving these equations yields v = 18 km/h and d = 21 km, which satisfies both conditions.

Multiple choice
  1. 47 km/h

  2. 52 km/h

  3. 42 km/h

  4. 45 km/h

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Lap 1: 200 km in 4h = 50 km/h. Lap 2: 162 km at 15 m/s = 54 km/h, time = 162/54 = 3h. Total average = 50 km/h. Total time needed = (total distance)/(avg speed) = (200 + 162 + d3)/50. Let t3 = 4h. Then (362 + d3)/50 = 4 + 3 + 4 = 11h, so d3 = 550 - 362 = 188 km. Speed in lap 3 = 188/4 = 47 km/h. Options B (52), C (42), and D (45) are incorrect.

Multiple choice
  1. 6

  2. 7

  3. 4

  4. 5

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Speed = distance/time = 225/2.5 = 90 km/h. For 630 km at same speed: time = distance/speed = 630/90 = 7 hours. This uniform speed problem requires calculating speed first, then applying it to the new distance. The key is maintaining the same speed throughout.

Multiple choice
  1. 7 hours

  2. 9 hours

  3. 5 hours

  4. 6 hours

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

After 7 hours, first person travels 28 km (4 × 7). Second person travels 1+2+3+4+5+6+7 = 35 km (sum of first 7 natural numbers, starting at 2 km/h). Total = 63 km, exactly the initial distance. At 6 hours, they'd only travel 24 + 21 = 45 km, which is less than 63 km.

Multiple choice
  1. 45 km

  2. 44 km

  3. 41 km

  4. 42 km

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Effective speeds in stream direction: A = 17 + 3 = 20 km/h, B = 23 + 3 = 26 km/h, C = 15 + 3 = 18 km/h. Time taken: A = 105/20 = 5.25 hours, B = 105/26 = 4.04 hours (winner), C = 105/18 = 5.83 hours. Distance between winner B and last C when B finishes: Distance by C = 18 × 4.04 = 72.7 km. Lead = 105 - 72.7 ≈ 42 km.

Multiple choice
  1. 20 hours

  2. 16 hours

  3. 12 hours

  4. 15 hours

  5. None of these

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since A and B meet at the midpoint, each travels 180 km. A travels for t hours, B starts 2 hours late so travels (t-2) hours. Equating distances: (x-2.5)t = 180 and (x+5)(t-2) = 180. Solving gives x = 25 and t = 8 hours to reach midpoint. Total time for full 360 km journey = 360/(x-2.5) = 360/22.5 = 16 hours.

Multiple choice
  1. 1028

  2. 1088

  3. 384

  4. 1152

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let usual time be t hours, stipulated time. Distance D = S × t. At 60 km/h: time = t + 20/60, so D = 60(t + 1/3) = 60t + 20. At 75 km/h: time = t - 44/60, so D = 75(t - 11/15) = 75t - 55. Equating: 60t + 20 = 75t - 55 → 15t = 75 → t = 5 hours. Then D = S × 5, and also D = 60 × 5 + 20 = 320, so S = 64 km/h. 3D + 3S = 3(320) + 3(64) = 960 + 192 = 1152. The problem involves two scenarios with different speeds and time deviations from stipulated time.