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

If two incorrect watches are set at 12:00 noon at correct time, when will both watches show the correct time for the first time given that the first watch gains 1 min in one hour and second watch looses 4 min in two hours.

• 1] 6 PM, 25 days later
• 2] 12 noon, 30 days later
• 3] 12 noon, 15 days later
• 4] 6 AM, 45 days later
• 5] None of these

A minibus takes 6 hour less to cover 1680 km distance, if its speed is increased by 14 kmph ? What is the usual time of the minibus ?

• 1] 15 hours
• 2] 24 hours
• 3] 25 hours
• 4] 30 hours

Two cyclists start from the same place in opposite directions. One goes towards north at 18 kmph and the other goes towards south at 20 kmph. What time will they take to be 47.5 km apart ?

• 1]

  \({ \text{1}}\frac{1}{4}{ \text{ hrs}}\)

• 2]

  \({ \text{2}}\frac{1}{4}{ \text{ hrs}}\)

• 3]

  2 hrs 23 min

• 4]

  \({ \text{2}}\frac{1}{2}{ \text{ hrs}}\)

Without stoppage, a train travels a certain distance with an average speed of 60 km/h, and with stoppage it covers the same distance with an average speed of 40 km/h. On an average, how many minutes per hour does train stop during the journey ?

• 1] 20 min/hour
• 2] 15 min/hour
• 3] 10 min/hour
• 4] 12 min/hour

Two guns were fired from the same place at an interval of 8 minutes. A person approaching the place observes that 5 minutes 52 seconds have elapsed between the hearing of the sound of the two guns. If the velocity of the sound is 330 m/sec, the man was approaching the place at what speed (in km/hr) ?

• 1] 24 km/hr
• 2] 27 km/hr
• 3] 30 km/hr
• 4] 36 km/hr

Two boats go downstream from point X to Y. The faster boat covers the distance from X to Y, 1.5 times as fast as slower boat. It is known that for every hour slower boat lags behinds the faster boat by 8 km. however, if they go upstream, then the faster boat covers the distance from Y to X in half the time as the slower boat. Find the speed of the faster boat in still water?

• 1] 12 kmph
• 2] 20 kmph
• 3] 24 kmph
• 4] 25 kmph
• 5] None of these

The speeds of three cars are the ratio 2 : 3 : 4. The ratio of the taken by these cars to travel the same distance is :

• 1] 2 : 3 : 4
• 2] 4 : 3 : 2
• 3] 4 : 3 : 6
• 4] 6 : 4 : 3

Two ports A and B are 300 km apart. Two ships leave A for B such that the second leaves 8 hours after the first. The ships arrive at B simultaneously. Find the time the slower ship spent on the trip if the speed of one of them is 10 km/h higher than that of the other.

• 1] 25 hours
• 2] 20 hours
• 3] 15 hours
• 4] 20 hours
• 5] 24 hours

A long distance runner run 9 laps of a 400 metres track everyday. His timings (in min) for four consecutive days are 88, 96, 89 and 87 respectively. On an average, how many metres/minutes does the runner cover ?

• 1] 17.78 m/min
• 2] 40 m/min
• 3] 90 m/min
• 4] None of these