If a boat is rowed downstream for 50 km in 5 hours and upstream for 24 km in 6 hours, what is the speed of the boat and the river?
Answer: A
If x: speed of boats man in still water
y: speed of the river
Downstream speed (Ds) = x + y
Upstream speed (Us) = x – y
x = (Ds + Us) / 2
y = (Ds – Us) / 2,/p>
In the above problem Ds = 10 ; Us = 4
x = (10 + 4) / 2 = 14/2 = 7 km/hr
y = (10 - 4)/2 = 6/2 = 3 km/hr
Enter details here
A boat covers a distance of 30 km in 2 ½ hours running downstream while returning it covers the same distance in 3 ¾ hours. What is the speed of the boat in still water?
Answer: D
Speed downstream = (30 x 2/5)km/hr = 12km/hr
Speed upstream = (30 x 4/15) km/hr = 8 km/hr
Speed of boat in still water = ½ (12 + 8)km/hr = 10 km/hr
Enter details here
A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and black. What is the total distance traveled by the man?
Answer: C
M = 6
S = 1.2
DS = 7.2
US = 4.8
x/7.2 + x/4.8 = 1
x = 2.88
D = 2.88 * 2 = 5.76
Enter details here
In a river, a man takes 3 hours in rowing 3 km upstream or 15 km downstream. What is the speed of the current?
Answer: A
Speed upstream = 3/3 km/hr =1 km/hr
Speed downstream = 15/3 km/hr = 5 km/hr
Speed of current = ½(5 -1) km/hr = 2 km/hr
Enter details here
Sahil can row 3 km against the stream in 20 minutes and he can return in 18 minutes. What is rate of current ?
Answer: A
No answer description available for this question.
Enter details here
A boats man can row in still water at speed of 7 km/hr. It takes 6 hours more to travel the same distance in upstream than in downstream if the speed of the river is 3 km/hr. what is the distance between the two destinations?
Answer: A
x = 7 km/hr ; y = 3 km/hr
Ds = 10 km/hr ; Us = 4 km/hr
Distance (d) is same. Therefore, if time taken for downstream is t hours, the time for upstream is (t + 6) hours.
10 × t = 4 × (t + 6)
6t = 24 ; t = 4 hours
d = 10 × 4 = 40 km
Enter details here
Michel can swim in still water at the rate of 6km per hour. After swimming in a stream, she realized that she takes twice the time to go upstream as she takes to go downstream. What is speed of the current?
Answer: B
No answer description available for this question.
Enter details here
A man can row three-quarters of a kilometer against the stream in 11 ¼ minutes and return in 7 ½ minutes. The speed of the man in still water is?
Answer: D
Distance covered upstream in 45/4min =3/4 km
Distance covered upstream in 1 hr =(3/4 × 2/15 × 60) km/hr = 4 km/hr
Distance covered downstream in 15/2 min = ¾ km
Distance covered downstream in 1hr
= (3/4 × 2/15 × 60)km/hr = 6 km/hr
Speed of the man in still water
= ½ (6 + 4)km/hr = 5 km/hr
Enter details here
The current of a stream at 1 kmph. A motor boat goes 35 km upstream and back to the starting point in 12 hours. The speed of the motor boat in still water is?
Answer: A
S = 1
M = x
DS = x + 1
US = x - 1
35/(x + 1) + 35/(x - 1) = 12
x = 6
Enter details here
A man can row with a speed of 15 kmph in still water. If the stream flows at 5 kmph, then the speed in downstream is?
Answer: C
No answer description available for this question.
Enter details here