- In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/ hr and the time of flight increased by 30 minutes. The duration of the flight is:
(a) 1 hours (b) 2 hours (c) 3 hours (d) 4 hours
- Points A and B are 70 km apart on a highway. One car starts from A and the another one from B at the same time. If they travel in the same direction, they meet in 7 hours. But if they travel towards each other, they meet in one hour. The speeds of the two cars are, respectively. (a) 45 and 25 km/h (b) 70 and 10 km/h (c) 40 and 30 km/h (d) 60 and 40 km/h
- Anil calculated that it will take 45 minutes to cover a distance of 60 km by his car. How long will it take to cover the same distance if the speed of his car is reduced by 15 km/hr?
(a) 36 min (b) 55.38 min (c) 48 min (d) 40 min
- The jogging track in a sports complex is 726 metres in circumference. Pradeep and his wife start from the same point and walk in opposite directions at 4.5 km/h and 3.75 km/h, respectively. They will meet for the first time in :
(a) 5.5 min (b) 6.0 min (c) 5.28 min (d) 4.9 min
- A river 3 m deep and 40 m wide is flowing at the rate of 2 km per hour. How much water (in litres) will fall into the sea in a minute?
(a) 4,00,000 (b) 40,00,000 (c) 40,000 (d) 4,000
- The speed of a boat in still water is 15 km/h and the rate of stream is 5 km/h. The distance travelled downstream in 24 minutes is (a) 4 km (b) 8 km (c) 6 km (d) 16 km
- A person can swim in still water at 4 km/h. If the speed of water is 2 km/h, how many hours will the man take to swim back against the current for 6 km.
(a) 3 (b) 4 (c) 1 4 2 (d) Insufficient data
- A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water?
(a) 4 km/h (b) 6 km/h (c) 8 km/h (d) Data inadequate
- A boat goes 24 km upstream and 28 km downstream in 6 hours. It goes 30km upstream and 21 km downstream in 6 hours and 30 minutes. The speed of the boat in still water is :
(a) 10 km/h (b) 4 km/h (c) 14 km/h (d) 6km/h
- A man who can swim 48 m/min in still water swims 200 m against the current and 200 m with the current. If the difference between those two times is 10 minutes, find the speed of the current. (a) 30 m/min (b) 29 m/min (c) 31 m/min (d) 32 m/min
Answers and Solutions
- (a) Let the duration of the flight be x hours.
Then, x = 1hr
- (c) Let the speed of the cars be x km/h and y km/h respectively.
Their relative speed when they are moving in same direction = (x – y) km/h.
Their relative speed when they are in opposite directions = (x + y) km/h.
Now, 70x+y= 1 or or x + y = 70 ….. (i) and
70x-y= 7 or x – y = 10 ….. (ii)
Solving (i) and (ii), we get x = 40 km/h and y = 30 km/h.
- (b) D = S × T
60 = S 4560hr
S =- 80km/hr
Now, new speed = 80 – 15 = 65 km/hr.
Time Distance/Speed 6065hr or 55.38min.
Hence, Time to taken by car to travel same distance is 55.38 min.
- (c) Let the husband and the wife meet after x minutes. 4500 metres are covered by Pradeep in 60 minutes.
In x minutes, he will cover 450060x metres.
In x minutes, his wife will cover 375060x m.
Now, x = 5.28 min
- (b) Volume of water flowed in an hour
= 2000 × 40 × 3 cubic metre = 240000 cubic metre
volume of water flowed in 1 minute
= 24000060=4000 = cubic metre = 40,00,000 litre
- (b) Downstream speed = 15 + 5 = 20 km/h.
Required distance = 20 2460= 8km
- (a) Man’s speed in upstream = 4 – 2 = 2 km/h.
Required time = 63km/ h = 2km/hr
- (b) Rate downstream = 162 kmph = 8 kmph;
Rate upstream = 164kmph = 4 kmph.
Speed in still water = 12(8 + 4) = 6 km/h.
- (a) Let speed of the boat in still water be x km/h and speed of the current be y km/h.
Then, upstream speed = (x – y) km/h
and downstream speed = (x + y) km/h
24x-y + 28x+y = 6 ….. 1
And 30x-y+ 21x+y= 132…… 2
From equation 1 and 2
Now, x = 10km/hr and y = 4km/hr