Q1 . The time taken by a boat to go upstream is 2 hours.The total distance travelled by the boat is 60 kms and the speed of the boat in still water is 18 km/h,Then find the speed of the river water?
1. 2 km/h
2. 4 km/h
3. 5 km/h
4. 3 km/h
Correct Answer is
3 km/h
SOLUTION
let the speed of river be s
If the total distance 60 then upstream and downstream would be 30 each
so upstream time is 30/18-s=2
solving we get s=3 km/h
Q2 . The time taken by a boat to go upstream and down stream is 4 hours totally.The speed of the boat in still water is 4 km/h amd the speed of the river water is 2 km/h.What is the total distance covered by the boat?
1. 7 km
2. 8 km
3. 6 km
4. 12 km
Correct Answer is
6 km
SOLUTION
let the distance be d
upstream time is d/4-2
downstream time d/4+2
total time is 4 hours
d/(4-2) +d/(4+2)=4
solving we get d= 6 km
Q3 . The distance between a point downstream and one at the upstream end is D.The speed of the boat is one fourth the distance and the the speed of the stream is half the speed of the boat.what is the time taken to go upstream?
1. 8 hrs
2. 9 hrs
3. 18 hrs
4. 12 hrs
Correct Answer is
8 hrs
SOLUTION
The distance be d
speed of boat is d/4
speed of the stream is d/8
time taken=distance/time
time=d/(d/4-d/8)
time is 8 hrs
Q4 . The time taken by the boat to go upstream is double the speed of the boat in still water and which is twice the speed of the river water.The speed of the stream is 2km/h.what is the total distance covered by the boat?
1. 14 km
2. 12 km
3. 15 km
4. 16 km
Correct Answer is
16 km
SOLUTION
let us assume the speed of river to be s
speed of boat is 2s
time taken should be 2x2s=4s
upstream time=d/2s-s
4s=d/(2s-s)
we know that s=2 km/h
so now solving we get d=16 km
Q5 . The time taken by a boat to go upstream is 4 hours .The total distance covered by the boat going upstream and downstream is 32 km.If the speed of the stream is 1km/h.Find the speed of the boat?
1. 6 km/h
2. 5 km/h
3. 8 km/h
4. 5.5 km/h
Correct Answer is
5 km/h
SOLUTION
total distance is 32 km so one way distance is 16 km