TSD-3
Boats and Streams a) 120km b) 270 km
1. A man takes 5 hr 15 min to row a boat 21 km c) 180 km d) 90 km
downstream and 2 hr 15 min to cover a d) 210 km
distance of 6 km upstream. Find the speed (in
km/hr) of the river current. 7. A boat travels 24 km upstream in 6 hours and
10 4 20 km downstream in 4 hours. Then the
a) b)
3 3 speed of boat in still water and the speed of
2 5 water current are respectively:
c) d)
3 3 a) 4 kmph and 3 kmph
b) 4.5 kmph and 0.5 kmph
2. Sam can row 18 km downstream in 4 hr. his c) 4 kmph and 2 kmph
return journey takes 12 hr. What is the speed d) 5 kmph and 2 kmph
(in km/hr) of the current?
a) 1.5 b) 3 8. A boat covers 12 km upstream and 18 km
c) 2 d) 4 downstream in 3 hours, while it covers 36 km
1
upstream and 24 km downstream in 62
3. A man goes downstream at X km/hr and
upstream at Y km/hr. what is the speed of the hours. What is the speed of the current?
man in still water? a) 1.5 km/hr b) 1 km/hr
a) 0.5(x+y) km/hr b) 0.5(x-y)km/hr c) 2 km/hr d) 2.5 km/hr
c)(x+y) km/hr d)(x-y) km/hr
9. A man can swim 3 km/hr in still water. If the
3 velocity of the stream is 2 km/hr, the time
4. A man can row 8th of a km upstream in 30
taken by him to swim to a place 10 km
min and return in 12 min. find the speed of upstream and back is
the boat in still water. 1
21 21 a) 9 hr b) 10 hr
a) km/hr b) km/hr 3
1
13 16
19 19 c) 12 hr d) 8 hr
c) km/hr d) km/hr 3
16 13
17
e) km/hr 10. A swimmer swims from a point A against a
16 current for 5 minutes and then swims back in
favour of the current for next 5 minutes and
5. A boat takes 10 minutes to reach a place comes to the point B. If AB is 100 meters, the
upstream. It can come back to the same place speed of current (in km per hour) is
in 5 min, down the stream. If the speed of the a) 0.4 b) 02.
stream is 2 m/sec, then what is the speed of c) 1 d) 0.6
the boat?
a) 6 m/sec b) 4 m/sec 11. A man can row 30km downstream and
c) 8 m/sec d) 5 m/sec return in a total of 8 hours. If the speed of the
d) 2.5 m/sec boat in still water is four times the speed of
the current, then the speed of the current is
6. A boat takes 22 hours for travelling a) 1 km/hr b) 2 km/hr
downstream from point P to point Q and c) 4 km/hr d) 3 km/hr
coming back to point R midway between P
and Q. if the speed of the stream is 3 kmph
and speed of the boat in still water is 12
kmph, then what is the distance between P
and Q?
CEX-Q-2050
12. Two boats A and B start towards each other 18. A man can walk up a moving ‘up’ escalator in
from two places, 108 km apart. Speeds of the 30s. The same man can walk down this
boats A and B in still water are 12km/hr and moving ‘up’ escalator in 90s. Assume that his
15km/hr respectively. If A proceeds down walking speed is same upwards and
and B up the stream, they will meet after downwards. How much time will he take to
a) 4.5 hours b) 4 hours walk up the escalator, when it’s not moving?
c) 5.4 hours d) 6 hours
13. Speed of motorboat in still water in 45kmph. 19. Ram always walks down on a moving
If the motorboat travels 80km along the escalator to save time. He takes 50 steps
stream in 1 hour 20 minutes, then the time while he goes down. One day due to power
taken by it to cover the same distance against failure of 10 secs (when the escalator comes
the stream will be to a halt) he takes 9 secs more than usual
a) 3 hours b) 1 hour 20 minutes time to get down. Find the visible steps of the
c)2 hours 40 minutes d)2 hours 55 minutes escalator.
14. A boatman rows 1 km in 5 minutes, along the
stream and 6 km in 1 hour against the stream. 20. Rohan walked down a descending escalator
The speed of the stream is and took 40 steps to reach the bottom. Sohan
a) 3kmph b) 6kmph started simultaneously from the bottom,
c) 10kmph d) 12kmph taking 2 steps to every 1 step taken by Rohan.
Time taken by Rohan to reach the bottom
Escalators: from the top is the same as time taken by
15. A man and his wife walk up a moving Sohan to reach the top from the bottom.
escalator. The man walks twice as fast as his 1) How many steps more than Rohan did
wife. When he arrives at the top, he has taken Sohan take before they crossed each other?
28 steps. When she arrives at the top, she has 2) If Rohan were to walk at the speed of
taken 21 steps. How many steps are visible in Sohan, what % of the initial time would he
the escalator at any one time. able to save?
16. A woman is walking down a downward- Direction for Questions 21 – 22. Jordan
moving escalator and steps down 10 steps to wanted to climb down from the first floor to
reach the bottom. Just as she reaches the the ground floor of a shopping mall, whereas
bottom of the escalator, a sale commences on Karina wanted to climb up from the ground
the floor above. She runs back up the floor to the first floor. Both use the same
downward moving escalator at a speed five escalator which was ascending from the
times that which she walked down. She ground floor to the first floor and both
covers 25 steps in reaching the top. How walked their respective destinations. Both of
many steps are visible on the escalator when them started simultaneously from the top and
it is switched off? the bottom of the escalator respectively and
crossed each other after exactly 21 seconds. If
instead, Karina had walked at of his speed
17. A famous mathematician who is always in a while Jordan maintained his speed, they
hurry walks up an up-going escalator at the would have crossed each other after exactly
rate of one step per second. Twenty steps 28 seconds from the start. Further if both
bring him to the top. The next day he goes up Jordan and Karina had climbed up from the
at two steps per second, reaching the top in ground floor to the first floor using the same
32 steps. How many steps are there in the ascending escalator, the number of steps
escalator? taken by Karina to reach the first floor would
be 20% less than the number of steps taken
by Jordan for the same.
CEX-Q-2050
21. If Jordan were to stand still on the same 26. Ravi takes 40 seconds to walk up on an
escalator, how long would it take for the escalator which is moving upwards but he
escalator to take him from the ground floor to takes 60 seconds to walk up on an escalator
the first floor? which is moving downwards. How much time
a) 42 sec b) 63 sec will he take to walk up if the escalator is not
c) 4 sec d)105 sec moving?
e) None
22. Jordan walked down from the first floor to
the ground floor using the same escalator.
However, after some time the escalator
stopped moving due to a power failure. Find
the total time taken by Jordan to reach the
ground floor, given that the time for which he
walked on the moving escalator was the same
as that for which he walked on the stationary
escalator.
Direction for Questions 23 – 24. Ann
walked up a descending escalator and took
154 steps in 100 seconds to reach the top.
Karen started simultaneously from the top,
taking 3 steps for every 4 steps of Ann, and
reached the bottom in 40 seconds.
23) How many steps from the bottom were
they, when they crossed each other?
a) 22 b) 25
c) 30 d) 33
e) 36
24) Find the number of steps between Ann
and Karen exactly seconds after they started
walking on the escalator.
a) 21 b) 49
c) 28 d) 54
e) 42
25. On an upward moving escalator, Amar, Akbar
and Anthony take 10 steps, 8 steps, and 5
steps, respectively, to reach the top. On the
same upward moving escalator Amar takes
30 steps to come down from the top. Find the
ratio of the time taken by Akbar and Anthony
to reach the top.
CEX-Q-2050
