12
Q:

# A man goes down stream with a boat to some destination and returns upstream to his original place in 5 hours. If the speed of the boat in still water and the strean are 10km/hr and 14km/hr respectively, the distance of the destination from the string place is

 A) 16 km B) 18 km C) 21 km D) 25 km

Answer:   C) 21 km

Explanation:

Let the distance covered be D km.

$D14+D6=5$

10D = 42 x 5 = 210

=> D = 21 km

Q:

A boat can move 5 km/hr in still water. If the river is running at 1 km/hr, it takes it 75 min to move to a place and back. How far is the place?

 A) 3 kms B) 5 kms C) 6 kms D) 4 kms

Answer & Explanation Answer: A) 3 kms

Explanation:

Let the place be at a distance of 'd' kms

From the given data,

5d/12 = 5/4 => d = 3 kms.

Hence, the place is 3 kms far.

0 36
Q:

If the boat goes 7 kms upstream in 42 min and speed of the stream is 3 kmph, then the speed of the boat in still water ?

 A) 14 kmph B) 13 kmph C) 12 kmph D) 11 kmph

Answer & Explanation Answer: B) 13 kmph

Explanation:

Given that, upstream distance = 7 kms

Upstream speed = 7/42 x 60 = 10 kms

Speed of the stream = 3 kmph

Let speed in still water = M kmph, then

Upstream speed = M - 3 = 10

=> M = 13 kmph.

1 62
Q:

Sravan drove from home to a neighboring town at the speed of 50 km/h and on his returning journey, he drove at the speed of 45 km/h and also took an hour longer to reach home. What distance did he cover?

 A) 350 kms B) 450 kms C) 900 kms D) 700 kms

Answer & Explanation Answer: C) 900 kms

Explanation:

Let the distance he covered each way = d kms

According to the question,

d/45 - d/50 = 1

=> d = 450 kms.

Hence, the total distance he covered in his way = d + d = 2 d = 2 x 450 = 900 kms.

1 156
Q:

A boat while travelling upstream covers a distance of 29 km at the speed of 6 km/h, whereas while travelling downstream it covers the same distance at a speed of 12 km/h. What is the speed of the boat in still water?

 A) 6 kmph B) 8 kmph C) 9 kmph D) 11 kmph

Answer & Explanation Answer: C) 9 kmph

Explanation:

Speed of boat in still water = 1/2 (12 + 6) = 9 kmph.

2 476
Q:

A Woman’s downstream swimming rate is thrice of her upstream swimming rate. If she covers 12 km upstream in 2.5 hours, what distance she will cover in 5 hours downstream?

 A) 72 km B) 36 km C) 56 km D) 42 km

Answer & Explanation Answer: A) 72 km

Explanation:

Rate of her upstream = 12/2.5 = 4.8 km/hr

Then, ATQ

Rate of downstream = 4.8 x 3 = 14.4 km/hr

Hence, the distance she covers downstream in 5 hrs = 14.4 x 5 = 72 kms.

3 882
Q:

A man went downstream for 28 km in a motor boat and immediately returned. It took the man twice as long to make the return trip. If the speed of the river flow were twice as high, the trip downstream and back would take 672 minutes. Find the speed of the boat in still water and the speed of the river flow.

 A) 12 km/hr, 3 km/hr B) 9 km/hr, 3 km/hr C) 8 km/hr, 2 km/hr D) 9 km/hr, 6 km/hr

Answer & Explanation Answer: B) 9 km/hr, 3 km/hr

Explanation:

Let the speed of the boat = p kmph

Let the speed of the river flow = q kmph

From the given data,

=> 56p - 56q -28p - 28q = 0

=> 28p = 84q

=> p = 3q.

Now, given that if

Hence, the speed of the boat = p kmph = 9 kmph and the speed of the river flow = q kmph = 3 kmph.

2 1722
Q:

Rajesh rows in still water with a speed of 4.5 kmph to go to a certain place and comes back. Find his average speed for the whole journey, if the river is flowing with a speed of 1.5 kmph?

 A) 2 kmph B) 4 kmph C) 6 kmph D) 8 kmph

Answer & Explanation Answer: B) 4 kmph

Explanation:

Let the distance in one direction = k kms

Speed in still water = 4.5 kmph

Speed of river = 1.5

Hence, speed in upstream = 4.5 - 1.5 = 3 kmph

Speed in downstream = 4.5 + 1.5 = 6 kmph

Time taken by Rajesh to row upwards = k/3 hrs

Time taken by Rajesh to row downwards = k/6 hrs

Now, required Average speed =

Therefore, the average speed of the whole journey = 4kmph.

1 1068
Q:

A boat takes 2 hours to travel from point A to B in still water. To find out its speed upstream, which of the following information is/are required?

A. Distance between point A and B.

B. Time taken to travel downstream from B to A.

C. Speed of the stream of water.

 A) Only A and B B) Only B and C C) All are required D) Any one pair of A and B, B and C or C and A is sufficient

Answer & Explanation Answer: D) Any one pair of A and B, B and C or C and A is sufficient

Explanation:

Let distance between A & B = d km
Let speed in still water = x kmph
Let speed of current = y kmph

from the given data,
d/x = 2

From A) we get d
From B) we get d/x+y
From C) we get y

So, Any one pair of A and B, B and C or C and A is sufficient to give the answer i.e, the speed of upstream.