Time, Speed and Distance Questions

Multiple choice
  1. 60 minutes

  2. 64 minutes

  3. 68 minutes

  4. 72 minutes

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

When walking at 3/4 of normal speed, time becomes 4/3 of usual time. The extra time is (4/3 - 1) × usual time = 24 minutes. So (1/3) × usual time = 24, giving usual time = 72 minutes. Verification: At 3/4 speed, time = 72 × 4/3 = 96 minutes, which is 24 minutes more than usual.

Multiple choice
  1. $8(2/3) hrs.$
  2. $6(1/2) hrs.$
  3. $13 hrs.$
  4. $5(1/5) hrs.$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Downstream speed = Man's speed in still water + Stream speed = 5 + 3 = 8 km/hr. Time = Distance/Speed = 52/8 = 6.5 hours = 6(1/2) hours. When swimming downstream, the stream assists the swimmer, so effective speed is additive.

Multiple choice
  1. 572

  2. 584

  3. 564

  4. 612

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

Initial speed = 32 kmph (distance in 1st hour). Speed increases by 4 kmph each hour: 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72. Total distance = sum of this arithmetic progression = 11/2 × (2×32 + 10×4) = 11/2 × 104 = 572 km. Option D (612) would result from using n = 12 instead of 11 hours.

Multiple choice
  1. 32

  2. 36

  3. 40

  4. 48

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

Let usual speed = x km/hr. Time at usual speed = 480/x hours. At reduced speed (x-8) km/hr, time = 480/(x-8) hours. Given: 480/(x-8) - 480/x = 3. Solving: 480x - 480(x-8) = 3x(x-8). 480x - 480x + 3840 = 3x² - 24x. 3x² - 24x - 3840 = 0. Dividing by 3: x² - 8x - 1280 = 0. Using quadratic formula: x = [8 ± √(64 + 5120)]/2 = [8 ± √5184]/2 = [8 ± 72]/2. x = 40 or x = -32 (reject negative). Speed = 40 km/hr. This matches option C.

Multiple choice
  1. $520 m$
  2. $620 m$
  3. $720 m$
  4. $750 m$
  5. Cannot be determined

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

The distances form an AP: 50, 90, 130, ... with first term a = 50 and common difference d = 40. This is distance covered BY THE END of each minute. Sum of 15 terms = 15/2 × [2(50) + (15-1)(40)] = 15/2 × [100 + 560] = 15/2 × 660 = 4950 m. If the problem asks for distance covered IN 15 minutes (not total), we need the 15th term alone: 50 + 14×40 = 610 m. The closest option is B (620 m). Options A (520), C (720), and D (750) don't match.

Multiple choice
  1. 2010

  2. 2012

  3. 2014

  4. Cannot be determinded

  5. None of these

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

Speed of current = 4 km/hr, speed of boat = 15 × 4 = 60 km/hr. Downstream speed = 60 + 4 = 64 km/hr. Time for 2304 km downstream = 2304/64 = 36 hours. Upstream speed = 60 - 4 = 56 km/hr. Distance upstream in 36 hours = 56 × 36 = 2016 km. None of A (2010), B (2012), or C (2014) match 2016 km.

Multiple choice
  1. 1

  2. 2

  3. 3

  4. 4

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

Total time = 2 days 8 hours = 56 hours. Total distance = 3584 km. Average speed for entire journey = 3584/56 = 64 km/hr. Remaining distance after 2 days = 3584 - 1440 - 1608 = 536 km covered in 8 hours, so average speed = 536/8 = 67 km/hr. Difference = 67 - 64 = 3 km/hr.

Multiple choice
  1. 5.5 hours/घंटे

  2. 4 hours/घंटे

  3. 3 hours/घंटे

  4. 5 hours/घंटे

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

Let boat speed in still water = b kmph, stream speed = 3 kmph. Downstream speed = b + 3, upstream speed = b - 3. If distance is D, then D/(b+3) = 1 hour, and D/(b-3) = 1.5 hours. So D = b + 3 and D = 1.5(b - 3). Equating: b + 3 = 1.5b - 4.5, so 0.5b = 7.5, b = 15 kmph. Time for 75 km in still water = 75/15 = 5 hours. The key is to find the boat's speed in still water first using the ratio of downstream and upstream times.

Multiple choice
  1. 7.20 km./hr./किमी./घं

  2. 8.4 km./hr./किमी./घं

  3. 8.5 km./hr./किमी./घं

  4. 9 km./hr./ किमी./घं

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

Relative speed between cyclist and runner = 100 m / 5 min = 100/300 m/s = 1/3 m/s = 1.2 km/hr. Cyclist speed = Runner speed + Relative speed = 6 + 1.2 = 7.2 km/hr.

Multiple choice
  1. 30 kmph / किमी./घण्टा

  2. 25 kmph / किमी./घण्टा

  3. 20 kmph / किमी./घण्टा

  4. 15 kmph / किमी./घण्टा

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

Downstream speed (boat + current) = 40 km/h since 40 km is covered in 1 hour. Upstream speed (boat - current) = 20 km/h since 40 km takes 2 hours. Adding these equations: 2 × boat speed = 60, so boat speed = 30 km/h.

Multiple choice
  1. 15 kmph

  2. 5 kmph

  3. 10 kmph

  4. 12 kmph

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

Downstream speed = 30/2 = 15 kmph. Upstream speed = 30/6 = 5 kmph. Let boat speed = b, current speed = c. Downstream: b + c = 15. Upstream: b - c = 5. Given c = b/2 (current is half of boat speed). Substituting: b + b/2 = 15 gives 3b/2 = 15, so b = 10 kmph. Check: c = 5 kmph, which satisfies both equations. Option C is correct.

Multiple choice
  1. 42

  2. 40

  3. 35

  4. 45

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

Average speed = Total distance / Total time. Let total distance = D. Time for each part: first 50% at 50 kmph = 0.5D/50 = D/100 hours. Next 40% at 40 kmph = 0.4D/40 = D/100 hours. Remaining 10% at 20 kmph = 0.1D/20 = D/200 hours. Total time = D/100 + D/100 + D/200 = 5D/200 = D/40. Average speed = D / (D/40) = 40 kmph. Option B is correct. Option A (42) and D (45) incorrectly weight the speeds.

Multiple choice
  1. 33.33

  2. 30

  3. 28

  4. 25

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

For average speed, we need total distance divided by total time, not the average of speeds. Let total distance be 12 units (LCM of 3, 4, and remaining 5). Time taken: 4 units at 20 km/h = 0.2h, 3 units at 30 km/h = 0.1h, 5 units at 50 km/h = 0.1h. Total time = 0.4h, so average speed = 12/0.4 = 30 km/h. Option A (33.33) incorrectly averages the speeds.