Quiz Discussion

A star is 8.1 × 1013 km away from the earth. Suppose light travels at the speed of 3.0 × 105 km per second. How long will it take the light from the star to reach the earth ?

• 1] 7.5 × 103 hours
• 2] 7.5 × 104 hours
• 3] 2.7 × 1010 seconds
• 4] 2.7 × 1011 seconds

A dog start chasing to a cat 2 hour later. It takes 2 hours to dog to catch the cat. If the speed of the dog is 30 km/h. what is the speed of cat?

• 1] 10 km/h
• 2] 12 km/h
• 3] 15 km/h
• 4] 20 km/h

A plane left half an hour later than the scheduled time and in order to reach its destination 1500 kilometers away in time, it had to increase its speed by 33.33 percent over its usual speed. Find its increased speed.

• 1] 250 kmph
• 2] 500 kmph
• 3] 750 kmph
• 4] 1000 kmph
• 5] 1200 kmph

A train travels at a speed of 30 km/hr for 12 minutes and at a speed of 45 km/hr for the next 8 minutes. The average speed of the train for this journey is :

• 1] 30 km/hr
• 2] 36 km/hr
• 3] 37.5 km/hr
• 4] 48 km/hr

The length of a train and that of a platform are equal. If with a speed of 90 km/hr the train crosses the platform in one minute, then the length of the train (in meters) is ?

• 1] 500 meters
• 2] 600 meters
• 3] 750 meters
• 4] 900 meters

With an average speed of 50 km/hr, a train reaches its destination in time. If it goes with an average speed of 40 km/hr, it is late by 24 min. The total journey is :

• 1] 30 km
• 2] 40 km
• 3] 70 km
• 4] 80 km

A is travelling at 72 km per hour on a highway while B is travelling at a speed of 25 mitres per second. What us the difference in their speeds in mitres per second ?

• 1]

  \(1\frac{1}{2} \)m/sec

• 2]

  2 m/sec

• 3]

  3 m/sec

• 4]

  5 m/sec

Starting from his house one day,a student walks at a speed of 2.5 kmph and reaches his house 6 minutes late.Next day he increases his speed by 1kmph and reaches school 6 minutes early.How far is the school from his house.

• 1]

  7/4 km

• 2]

  3/2 km

• 3]

  4/5 km

• 4]

  1/2 km

Two trains of equal length, running in opposite directions, pass a pole in 18 and 12 seconds. The trains will cross each other in:

• 1] 14.4 seconds
• 2] 15.5 seconds
• 3] 18.8 seconds
• 4] 20.2 seconds

A train running at \(\frac{7}{11}\) of its own speed reached a place in 22 hours. How much time could be saved if the train would have run at its own speed?

• 1] 7 hr
• 2] 8 hr
• 3] 14 hr
• 4] 16 hr