Time, Speed and Distance Questions

Multiple choice
  1. $10\ a.m.$
  2. $10:30\ a.m.$
  3. $11\ a.m.$
  4. $11:30\ a.m.$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Train A travels for 1 hour alone (8am to 9am), covering 60 km. Remaining distance = 330 - 60 = 270 km. Relative speed = 60 + 75 = 135 km/hr. Time to meet = 270 / 135 = 2 hours after 9am, which is 11am.

Multiple choice
  1. $20$ kmph
  2. $5$ kmph
  3. $60$ kmph
  4. $30$ kmph
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let original speed be v. Time taken = 240/v. New time = 240/(v+20). Difference = 1 hour. 240/v - 240/(v+20) = 1. 240(v+20 - v) = v(v+20). 4800 = v^2 + 20v. v^2 + 20v - 4800 = 0. (v+80)(v-60) = 0. Original speed is 60 kmph.

Multiple choice
  1. $1000\text{km/h}$
  2. $1600\text{km/h}$
  3. $800\text{km/h}$
  4. $600\text{km/h}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let v be the usual speed. Time taken at usual speed is 1600/v, and at increased speed is 1600/(v+400). The difference is 40 minutes (2/3 hours). Solving 1600/v - 1600/(v+400) = 2/3 leads to v^2 + 400v - 960000 = 0. Factoring gives (v+1200)(v-800) = 0, so v = 800 km/h.

Multiple choice
  1. $100$km/hr
  2. $1000$km/hr
  3. $1050$km/hr
  4. $900$km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let v be the original speed. The time taken is 1500/v. With increased speed, time is 1500/(v+250). The difference is 0.5 hours. Solving 1500/v - 1500/(v+250) = 0.5 leads to v^2 + 250v - 750000 = 0. Factoring gives (v+1000)(v-750) = 0, so v = 750. The new speed is 750 + 250 = 1000 km/hr.

Multiple choice
  1. $30$ minutes
  2. $60$ minutes
  3. $40$ minutes
  4. $50$ minutes
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Speed ratio = 8:5:4. Time ratio = 1/8 : 1/5 : 1/4 = 5:8:10. Let times be 5x, 8x, 10x. Akbar takes 15 min more than Amar: 8x - 5x = 15 => 3x = 15 => x = 5. Antony's time = 10x = 50 minutes.