1. A man goes to his office from his house at a speed of 3 km/hr and returns at a speed of 2 km/hr. If he takes 5 hours in going and coming, what is the distance between his house and office?
1. 3 km
2. 4 km
3. 5 km
4. 6 km
Answer & Explanation Answer:- 4 Explanation :- Average Speed = 2(S1 * S2)/(S1 + S2) 2. A man rides his bicycle 10 km at an average speed of 12 km/hr and again travels 12 km at an average speed of 10 km/hr. What is his average speed for the entire trip approximately? Answer & Explanation Answer:- 4 Explanation :- Total Distance = 10 +12 = 22 km 3. An aeroplane covers a certain distance at a speed of 240 kmph in 5 hours. To cover the same distance in (1 & 2/3) hours, it must travel at a speed of: Answer & Explanation Answer:- 4 Explanation :- Distance = Speed * Time = (240 x 5) = 1200 km. 4. A train can travel 50% faster than a car. Both start from point A at the same time and reach point B 75 kms away from A at the same time. On the way, however, the train lost about 12.5 minutes while stopping at the stations. What is the speed of the car? Answer & Explanation Answer:- 3 Explanation :- Lets assume the speed of car = x km/h. 5. In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/hr and the time of flight increased by 30 minutes. What is the duration of the flight ? Answer & Explanation Answer:- 4 Explanation :- Assume the duration of the flight be x hours.
Here, S1 = 3 km/h & S2 = 2 km/h
Average Speed = (2 * 3 * 2 ) / ( 3 + 2 ) = 12/5 km/h
Time = 5 hours
Distance Covered = (12/5) * 5 = 12 km
Therefore , Distance between his house and office = 12/2 = 6 km
1. 11.2 kmph
2. 10 kmph
3. 10.2 kmph
4. 10.8 kmph
Time taken to cover 10 km with speed 12 km/h = 10/12 = 5/6 hrs
Time taken to cover 12 km with speed 10 km/h = 12/10 = 6/5 hrs
Total time = (5/6) + (6/5) = (25 + 36) / 30 = 61/30 hours
Average speed = Total Distance / Total Time = 22 / (61/30) = 660 / 61 = 10.8 km/ hour
1. 660 km/hr
2. 680 km/hr
3. 700 km/hr
4. 720 km/hr
For distance = 1200 km & Time = (1 & 2/3)hrs = 5/3 hrs
Speed = 1200 /(5/3) = 720 km/hr
1. 80 kmph
2. 102 kmph
3. 120 kmph
4. 140 kmph
Therefore, the speed of train = (3/2)x km/h = 1.5 km/h
Distance covered = 75 (same for both car and train)
Time taken by the car to cover 75 km = 75/x
Time taken by the train to cover 75 km = 75/1.5x
Difference in times = 12.5 minutes.
(75/x) – (75/1.5x) = (125/10×60)
x = 120
1. 2 hour
2. 112 hour
3. 12 hour
4. 1 hour
Therefore , Original Speed = 600/x
Speed due to bad weather = 600/ (x + 1/2)
(600/x) – [ 600/ (x + 1/2)] = 200
(600/x) – [ 1200/ (2x + 1)] = 200
x (2x +1) = 3
2x^2 + x – 3 = 0
(2x + 3) (x – 1) = 0
x = -3/2 & x = 1
By neglecting negative value of x , x = 1