Speed, Time and Distance
- A truck covers a distance of 368 km at a certain speed in 8 h. How much time would a car take at an average speed which is 18 km/h more than that of the speed of the truck to cover a distance which is 16 km more than that travelled by the truck ?
-
View Hint View Answer Discuss in Forum
Speed of truck = Distance/time = 368/8 = 46 km/h
Now, speed of car = (speed of truck + 18) km/h = (46 + 18) = 64 km/h and
Distance travelled by car = 368 + 16 = 384 kmCorrect Option: C
Speed of truck = Distance/time = 368/8 = 46 km/h
Now, speed of car = (speed of truck + 18) km/h = (46 + 18) = 64 km/h and
Distance travelled by car = 368 + 16 = 384 km
∴ Time taken by car = Distance/Speed = 384/64 h = 6 h
- Shantanu drives a motorcycle and covers a distance of 715 km at a constant speed.
If the speed of the motorcycle had been 10 km/h more, he would have taken 2 h less to cover the same distance. What is the original speed of the motorcycle?
-
View Hint View Answer Discuss in Forum
Let the constant speed = V
According to the question,
715/V - 715/(V + 10) = 2Correct Option: B
Let the constant speed = V
According to the question,
715/V - 715/(V + 10) = 2
⇒ 1/V - 1/(V + 10) = 2/715
⇒ [(V + 10) - V] / [V(V + 10)] = 2/715
⇒ V2 + 10V = 10 x 715/2
⇒ V2 + 10V - 3575 = 0
⇒ V2 + 65V - 55V - 3575 = 0
⇒ V(V + 65) - 55(V + 65) = 0
⇒ (V - 55) (V + 65) = 0
∴ V = 55 or V = - 65
Ignoring the negative value, we get V = 55
∴ Original speed of the motorcycle = 55 km/h
- The ratio of speeds of a train and a car is 16 : 15 , respectively and a bus covered a distance of 480 km in 8h. The speed of the bus is 3/4th of the speed of train. What will be covered by car in 6 h?
-
View Hint View Answer Discuss in Forum
Let speed of train = 16k
Speed of car = 15k
Speed of bus = 480/8 = 60 km/h
According to the question,
16k = 60 x 4/3 = 80Correct Option: A
Let speed of train = 16k
Speed of car = 15k
Speed of bus = 480/8 = 60 km/h
According to the question,
16k = 60 x 4/3 = 80
⇒ k = 5
∴ Speed of car = 15k = 15 x 5 = 75 km/h
∴ Required distance = Speed x Time
= 75 x 6 = 450 km
- Sumit drove at the speed of 45 km/h from home to a resort, returning over the same route, he got stuck in traffic and took an hour longer. Also, he could drive only at the speed of 40 km/h. How many kilometers did he drive each way ?
-
View Hint View Answer Discuss in Forum
Let distance he drove be L.
Using Time = Distance/speed
From given condition. L/40 - L/45 = 1Correct Option: B
Let distance he drove be L.
Using Time = Distance/speed
From given condition. L/40 - L/45 = 1
⇒ (45L - 40L)/(40 x 45) = 1
⇒ 5L = 40 x 45
⇒ L = 360 km
- A car runs at the speed of 40 km/h when not serviced and runs at 65 km/h when serviced. After servicing, the car covers a certain distance in 5 h. How much approximate time will the car take to cover the same distance when not serviced ?
-
View Hint View Answer Discuss in Forum
When serviced, the distance covered by the car = 65 x 5 = 325 km.
When not serviced, the time taken by the car to cover 325 km at 40 km/hCorrect Option: D
When serviced, the distance covered by the car = 65 x 5 = 325 km.
When not serviced, the time taken by the car to cover 325 km at 40 km/h
= 325/40 = 8.125 = 8 h (approx)