**Q1. A man**

rows upstream 11 km and downstream 26 km taking 5 hours each time. The velocity

of the current is.

rows upstream 11 km and downstream 26 km taking 5 hours each time. The velocity

of the current is.

(a) 3.5 km/h

(b) 2.5 km/h

(c) 1.5 km/h

(d) .5 km/h

**Q2. A man**

can row at 8 km/hr in still water. If the river is running at 4 km/hr, it takes

him 5 hours to row to a place and come back. How far is the place?

can row at 8 km/hr in still water. If the river is running at 4 km/hr, it takes

him 5 hours to row to a place and come back. How far is the place?

(a) 15 km

(b) 14 km

(c) 16km

(d) 17 km

**Q3. A man**

can row at 6 km/hr in still water. If the river is running at 2 km/hr, it takes

8 hours more in upstream than to go downstream for the same distance. How far

is the place?

can row at 6 km/hr in still water. If the river is running at 2 km/hr, it takes

8 hours more in upstream than to go downstream for the same distance. How far

is the place?

(a) 85 km

(b) 64 km

(c) 54 km

(d) None of

these

these

Q4. A man can row 6 km/hr in still water. It takes him twice as long to row up

as to row down the river. Find the rate of the stream.

Q4. A man can row 6 km/hr in still water. It takes him twice as long to row up

as to row down the river. Find the rate of the stream.

(a) 2 km/hr

(b) 3km/hr

(c) 1km/hr

(d) 1.5km/hr

S4. Ans.(a)

Sol. It takes

him twice as long to row up as to row down the river. It means upstream time is

twice of downstream time or we can say that downstream speed is two times of

upstream speed

him twice as long to row up as to row down the river. It means upstream time is

twice of downstream time or we can say that downstream speed is two times of

upstream speed

downstream

speed = 2 × upstream

speed = 2 × upstream

u + v = 2(u

– v)

– v)

6 + v = 2(6

– v)

– v)

v = 2 km/hr

**Q5. Manish**

can row at a speed of 4.5 km/hr in still water and rows to a certain upstream

point and back to the starting point in a river which flows at 1.5 km/hr. Find

his average speed for total journey.

can row at a speed of 4.5 km/hr in still water and rows to a certain upstream

point and back to the starting point in a river which flows at 1.5 km/hr. Find

his average speed for total journey.

(a) 3 km/hr

(b) 2 km/hr

(c) 5 km/hr

(d) 4 km/hr

**Q6. If a man**

rows 4 km downstream in 3 hours and 2 km upstream in 2 hours, then how long

will he take to cover 8 km in stationary (still) water?

rows 4 km downstream in 3 hours and 2 km upstream in 2 hours, then how long

will he take to cover 8 km in stationary (still) water?

(a) 5 hours

(b) 9 hours

(c)8 hours

(d) none of

these

these

S6. Ans.(d)

Sol. Distance

covered in downstream = 4 km

covered in downstream = 4 km

Time taken

in downstream = 3 hours.

in downstream = 3 hours.

Rate of

downstream = distance / time = a = 4km / 3 hours = 4/3 km/hr.

downstream = distance / time = a = 4km / 3 hours = 4/3 km/hr.

Distance

covered in upstream = 2 km

covered in upstream = 2 km

Time taken

in upstream = 2 hours.

in upstream = 2 hours.

Rate of

upstream = distance / time = b = 2 km / 2 hours = 1 km/hr.

upstream = distance / time = b = 2 km / 2 hours = 1 km/hr.

Speed in

still water = (a + b)/2 = (1/2)(4/3 + 1) km/hr = (1/2)(4 + 3)/3 = 7/6 km/hr.

still water = (a + b)/2 = (1/2)(4/3 + 1) km/hr = (1/2)(4 + 3)/3 = 7/6 km/hr.

Time Taken

to cover 8 km in still water = distance / speed = 8 x 6/7 = 48 / 7 = 7 hours

(approximately).

to cover 8 km in still water = distance / speed = 8 x 6/7 = 48 / 7 = 7 hours

(approximately).

**Q7. The**

speed of a boat in still water is 30 km/hr and the rate of current is 12 km/hr.

The distance traveled upstream in 20 minutes is-

speed of a boat in still water is 30 km/hr and the rate of current is 12 km/hr.

The distance traveled upstream in 20 minutes is-

(a) 6 km/hr

(b) 5 km/hr

(c) 9 km/hr

(d) 8 km/hr

**Q8. Sandeep**

can row a certain distance downstream in 5 hours and return the same distance

in 7 hours. If the stream flows at the rate of 2 km per hour. Find the speed of

Sandeep in still water.

can row a certain distance downstream in 5 hours and return the same distance

in 7 hours. If the stream flows at the rate of 2 km per hour. Find the speed of

Sandeep in still water.

(a) 14 km/h

(b) 15 km/h

(c) 13km/h

(d) 12 km/h

S8. Ans.(d)

Sol. In one

direction he will go by downstream and return with upstream and in both cases

distance is same

direction he will go by downstream and return with upstream and in both cases

distance is same

Downstream

distance = Upstream distance

distance = Upstream distance

(u + 2) 5 =

(u – 2) 7

(u – 2) 7

u = 12 km/h

**Q9. The rate**

of flow of river water is 4 km/hr. A boat goes 6 km and back to the starting

point in 2 hours. Find the speed of the boat in still water.

of flow of river water is 4 km/hr. A boat goes 6 km and back to the starting

point in 2 hours. Find the speed of the boat in still water.

(a) 6 km/hr

(b) 8 km/hr

(c) 9 km/hr

(d) 10 km/hr

**Q10. A man**

can row 30 km upstream and 44 km downstream in 10 hrs. Also, he can row 40 km

upstream and 55 km downstream in 13 hrs. Find the rate of the current(v) and

the speed of the man(u) in still water.

can row 30 km upstream and 44 km downstream in 10 hrs. Also, he can row 40 km

upstream and 55 km downstream in 13 hrs. Find the rate of the current(v) and

the speed of the man(u) in still water.

(a) u = 5, v

= 4

= 4

(b) u = 6, v

= 5

= 5

(c) u = 8, v

= 3

= 3

(d) None of

these

these

**Q11. A man**

can row 45 km upstream and 66 km downstream in 15 hrs. Also, he can row 65 km

upstream and 77 km downstream in 20 hrs. Find the speed of the man in still

water and rate of the current.

can row 45 km upstream and 66 km downstream in 15 hrs. Also, he can row 65 km

upstream and 77 km downstream in 20 hrs. Find the speed of the man in still

water and rate of the current.

(a) 8 km/hr,

3 km/hr

3 km/hr

(b) 11

km/hr, 3 km/hr

km/hr, 3 km/hr

(c) 11

km/hr, 8 km/hr

km/hr, 8 km/hr

(d) 9 km/hr,

2 km/hr

2 km/hr

**Q12. The**

speed of a boat in still water is 15 km/hr. It can go 30 km upstream and return

downstream to the original point in 4 hrs 30 min. The speed of the stream is:

speed of a boat in still water is 15 km/hr. It can go 30 km upstream and return

downstream to the original point in 4 hrs 30 min. The speed of the stream is:

(a) 5 km/hr

(b) 8 km/hr

(c) 10 km/hr

(d) 15 km/hr

**Q13. A boat goes 6 km in an hour in still**

water. It takes thrice as much time in covering the same distance against the

current. Speed of the current is:

water. It takes thrice as much time in covering the same distance against the

current. Speed of the current is:

(a) 2 km/hr

(b) 3 km/hr

(c) 4 km/hr

(d) 5 km/hr

**Q14. A**

swimmer’s speed downstream is 11 km/hr and speed of the steam is 1.5 km/h. Find

the upstream speed of swimmer.

swimmer’s speed downstream is 11 km/hr and speed of the steam is 1.5 km/h. Find

the upstream speed of swimmer.

(a) 8 km/hr

(b) 9.5

km/hr

km/hr

(c) 9 km/hr

(d) 6.25

km/hr

km/hr

**Q15. A person covers 18 km along the stream**

in 4 h and covers the same distance against the stream in 12 h. Find the speed

of stream in km/h.

in 4 h and covers the same distance against the stream in 12 h. Find the speed

of stream in km/h.

(a) 1

(b) 1.5

(c) 1.75

(d) 3