Time, Speed and Distance Questions

Multiple choice
  1. Quantity II > Quantity I

  2. Quantity I ≥ Quantity II

  3. Quantity I > Quantity II

  4. Quantity I ≤ Quantity II

  5. Quantity I = Quantity II

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

Quantity I: Time in still water = 28 ÷ 12 = 2.33 hours. Quantity II: Downstream speed = 12+4 = 16 km/hr, time = 32 ÷ 16 = 2 hours. Since 2.33 > 2, Quantity I > Quantity II.

Multiple choice
  1. I and III together

  2. Only II

  3. I and II together

  4. I and either II or III

  5. Any two statements together

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

We need two equations to find boat speed (b) and stream speed (s). Downstream speed = b + s = 25/5 = 5 kmph. Upstream speed = b - s = 25/10 = 2.5 kmph. Statement II: s = (2/3)b. I & III: 5 and 2.5 give b = 3.75, s = 1.25. Check II: (2/3)×3.75 = 2.5 ≠ 1.25, so II is inconsistent. I & II: b + (2/3)b = 5, gives b = 3, s = 2. III & II: b - (2/3)b = 2.5, gives b = 7.5, s = 5. These are inconsistent pairs, so we need exactly one consistent pair. Actually, any two statements together can solve (even if inconsistent), so option E is correct.

Multiple choice
  1. 115 km

  2. 120 km

  3. 130 km

  4. 125 km

  5. None of these इनमे से कोई नही

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

Speed of car = Distance/Time = 450/15 = 30 km/h. Speed of bus = Distance/Time = 540/30 = 18 km/h. Speed of truck = (Speed of car + Speed of bus)/2 = (30 + 18)/2 = 48/2 = 24 km/h. Distance travelled by truck in 5 hours = Speed × Time = 24 × 5 = 120 km.

Multiple choice
  1. 4hrs

  2. 8hrs

  3. 3hrs

  4. 2hrs

  5. None of these

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

Downstream speed = boat speed + stream speed = 10 + 6 = 16 kmph. Time = distance/speed = 80/16 = 5 hours. None of the given options (4, 8, 3, 2 hours) match the correct answer of 5 hours, so 'None of these' (E) is correct.

Multiple choice
  1. Only 1

  2. Only 2

  3. Both 1 and 2

  4. Neither 1 or 2

  5. None of these

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

From statement 1, downstream speed = 35/5 = 7 km/h = boat speed + current speed. From statement 2, upstream speed = 35/7 = 5 km/h = boat speed - current speed. Adding both equations: 2 x boat speed = 12, so boat speed in still water = 6 km/h. Both statements together are necessary.

Multiple choice
  1. 138

  2. 142

  3. 160

  4. 120

  5. 145

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

Let original speed = v km/hr, time = t hours, distance = d = vt. Condition 1: speed (v+20), time (t-0.5), so d = (v+20)(t-0.5). Condition 2: speed (v+30), time (t-1), so d = (v+30)(t-1). Equating: vt = (v+20)(t-0.5) = (v+30)(t-1). Solving: vt = vt - 0.5v + 20t - 10 gives 0.5v = 20t - 10. And vt = vt - v + 30t - 30 gives v = 30t - 30. Solving these: t = 4 hours, v = 90 km/hr. Distance d = 90 × 4 = 120 km.

Multiple choice
  1. 60 km

  2. 54 km

  3. 64 km

  4. 72 km

  5. None of these इनमे से कोई नहीं

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

Let original speed be v km/h and distance be d km. When speed increases by 4 km/h, time saved is 9/2 min. When speed decreases by 6 km/h, time lost is 8 min. Using d/(v+4) = d/v - 9/120 and d/(v-6) = d/v + 8/60, solving gives d = 72 km. Option D is correct.

Multiple choice
  1. 2.5 km/hr.

  2. 3 km/hr.

  3. 3.5 km/hr.

  4. 4 km/hr.

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

The boat's upstream speed = distance/time = 45/6 = 7.5 km/hr. Upstream speed = boat speed in still water - stream speed. Therefore, stream speed = 10 - 7.5 = 2.5 km/hr. The stream's current slows down the boat by 2.5 km/hr when going upstream. Option A is correct.

Multiple choice
  1. 24

  2. 30

  3. 45

  4. 42

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

For a round trip, the boat's downstream speed is 8+2=10 km/hr and upstream speed is 8-2=6 km/hr. Let the distance be d. Total time is d/10 + d/6 = 8 hours. Solving: (3d+5d)/30 = 8, so 8d = 240 and d = 30 km. The distance is the same in both directions, so we use the harmonic mean relationship.

Multiple choice
  1. 3 hours

  2. 4 hours

  3. 3.5 hours

  4. 2 hours

  5. None of these

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

Let normal speed = v km/h, normal time = t hours. v × t = 300. After accident: (v - 20) × (t + 1/6) = 300. Substituting t = 300/v: (v - 20)(300/v + 1/6) = 300. Solving gives v = 150 km/h, t = 2 hours.

Multiple choice
  1. 50 kmph

  2. 24 kmph

  3. 25 kmph

  4. 26 kmph

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

Average speed = 2ab / (a + b) when distances are equal. Here 2(20)(30) / (20 + 30) = 1200 / 50 = 24 kmph. This is the harmonic mean, not arithmetic mean (25 kmph). The formula derives from total distance (2d) divided by total time (d/a + d/b).