A boat can travel 48 km upstream in 6 hours. If the speed of the stream is 2 km/hr, how much time will the boat take to cover a distance of 120 km downstream?
A
20 hours
B
18 hours
C
10 hours
D
19 hours
উত্তরের বিবরণ
Question: A boat can travel 48 km upstream in 6 hours. If the speed of the stream is 2 km/hr, how much time will the boat take to cover a distance of 120 km downstream?
Solution:
Distance covered by a boat in 6 hours = 48 km
Rate upstream of boat = 48/6
= 8 km/hr
Now,
Speed of stream = 2 km/hr
∴ Speed of boat in still water = (8 + 2)
= 10 km/hr
∴ Rate downstream of boat = (10 + 2) km/hr
= 12 km/hr
∴ Time taken in covering 120 km distance = 120/12
= 10 hours
0
Updated: 1 month ago
A train passes two bridges of length 800 m and 400 m in 100 seconds and 60 seconds respectively. The length of the train is-
Created: 1 month ago
A
350 m
B
450 m
C
300 m
D
200 m
Question: A train passes two bridges of length 800 m and 400 m in 100 seconds and 60 seconds respectively. The length of the train is-
Solution:
Let the length of the train is x m and speed is s.
ATQ,
s = (x + 800)/100 and,
s = (x + 400)/60
∴ (x + 800)/100 = (x + 400)/60
or, 60x + 48000 = 100x + 40000
or, 40x = 8000
or, x = 200 m
0
Updated: 1 month ago
A train passes a man at 110 kmph running towards the train at the speed of 10 kmph. If it took 3 seconds to cross the man, what would be the length of the train?
Created: 1 month ago
A
300 m
B
100 m
C
250 m
D
180 m
Question: A train passes a man at 110 kmph running towards the train at the speed of 10 kmph. If it took 3 seconds to cross the man, what would be the length of the train?
Solution:
As both of them are facing towards each other.
total speed will be = 110 + 10 kmph
= 120 kmph
length of the train = 120 × (3/3600) km
= 0.1 km
= 100 m
0
Updated: 1 month ago
An aeroplane covers a certain distance at a speed of 250 kmph in 6 hours. To cover the same distance in 100 minutes, it must travel at a speed of-
Created: 1 month ago
A
900 km/hr
B
700 km/hr
C
800 km/hr
D
950 km/hr
Question: An aeroplane covers a certain distance at a speed of 250 kmph in 6 hours. To cover the same distance in 100 minutes, it must travel at a speed of-
Solution:
Total Distance = (250 × 6) = 1500 km.
Time 100 minutes = 100/60 hr
= 5/3 hr
We know that,
Speed = Distance/Time
∴ Required speed = 1500/(5/3) km/hr
= 900 km/hr.
0
Updated: 1 month ago
