** BEST 5 Shortcuts on Boats and Stream Problems for IBPS PO/Clerk Exams 2017**:

Dear Readers, Here we have given the BEST 5 Shortcuts on Boats and Stream Problems for IBPS PO/Clerk 2017, candidates those who are preparing for the upcoming SBI Clerk/IBPS Exams 2017 can make use of it

**BASIC CONCEPT OF BOATS AND STREAM**

**Still water:**

If the water is not moving then it is called still water.

Speed of boat in still water is= ยฝ (Downstream Speed + Upstream Speed)

**Stream:**

Moving water of the river is called stream

**Upstream:**

If a boat or a swimmer moves in the opposite direction of the stream then it is called upstream movement. In this case motion of boat or swimmer is **opposed** by the motion of stream.

**Downstream:**

If a boat or a swimmer moves in the same direction of the stream then it is called downstream movement. In this case motion of boat or swimmer is **supported** by the motion of stream.

When speed of boat or a swimmer is given then it normally means speed in still water.

Concepts and formulas of boats and streams are also applicable to problems involving:

**Cyclist and wind:**

Cyclist analogous to boat and wind analogous to stream.

**Swimmer and stream:**

Swimmer analogous to boat

If speed of boat in still water is โbโ km/hr and speed of stream is โsโ km/hr,

**Speed of boat downstream = (b+s) km/hr,** since the boat goes with the stream of water hence its speed increase.

**Speed of boat upstream = (b โ s) km/hr, **the boat goes against the stream of water and hence its speed gets reduced.

Distance = Speed ร Time

D = ST

**Type 1:**

**If Ratio of downstream and upstream speeds of a boat is a : b. then ratio of time taken = b : a**

Speed of stream = ((a – b)/ ( a + b))ร speed in still water.

Speed in still water = ((a + b) /(a โ b)) ร speed of stream.

__Example__:

**1) A man can row a boat to a certain distanced upstream in 4 hours and takes 3 hours to row downstream the same distance. What is the speed of boat in still water, if the speed of the stream is 2 km/hr?**

- a) 9km/hr b) 10 km/hr c) 12 km/hrย ย ย ย d) 14 km/hr

**Solution:**

Ratio of speed downstream and upstream = 3 : 4

Speed of boat in still water = ((4+3) / (4-3)) ร 2 = 14 km/hr

**2) A man can row a boat 120 km with stream in 5 hours. If speed of the boat is double the speed of the stream, find the speed stream?**

- a) 6 km/hr b) 8 km/hr c) 9 km/hrย ย ย ย d) 12 km/hr

**Solution:**

Speed of the boat downstream = 120/5 = 24 km/hr

Ratio of speed of boat and stream = 2 : 1, speed of stream = 1/3 *24 = 8 km/hr

**Type 2:**

**1) If a steam boat goes 8 km upstream in 40 minutes and the speed of stream is 5 km/hr, In still water what would be the speed of the boat?**

**Solution:**

Rate of stream = 8 x 60 / 40 = 12 km/h. [convert minutes to hour we multiplying by 60] the speed of stream is 5 km/h

Let speed in still water be x km / hr.

If stream speed 5 km then speed of upstream would be = (x โ 5) km/hr

Then, speed upstream = (x โ 5) km / hr.

So, x โ 5 = 12

x = 12 + 5 = 17 km/hr.

**Type 3:**

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

**Solution:**

Pavi’s speed upstream = 4.5 – 1.5 = 3 kmph

Pavi’s speed downstream = 4.5+1.5 = 6 kmph

Distance = X km

Time Taken in upstream = X/3

Time Taken in downstream = X/6

Average Speed = 2X/(X/3 + X/6 ) = 4 kmph

**Type 4:**

**When a boatโs speed in still water is ‘a’ km/h and river is flowing with a speed of ‘b’ km/h an time taken to cover the same distance downstream, then **

**Example:**

**1)A boatโs speed in still water is 10 km/h while river is flowing with speed of 2 km/h and time to cover a certain distance upstream is 4 h more than time taken to cover the same distance downstream. Find the distance.**

**Solution:**

Here, a =10 km/h, b = 2 km/h, T = 4 h

By using formula:

Required distance = [(10^2 โ 2^2)/(2ร2)]x4

= 96 km

**Type 5:**

**Speed of boat in still water & speed of stream are given. Find average speed of boat that covers certain distance& returns through the same path.**

**Example:**

**1) If the speed of boat in still water is 10 km/hr & the speed of stream is 3 km/hr, the boat rows to a place which is 50 km far & returns through the same path. What would be the average speed of boat during the journey?**

a) 2 km/hr b) 4.5 km/hr c) 9.1 km/hrย ย d) 15 km/hr

**Solution:**

If a boat moves at ‘x’ km/hr speed and covers the same distance up and down in a stream at the speed of ‘y’ km/hr, then average speed is calculated by,

Speed of boat in still water = x = 10 km/hr

Speed of stream = y = 3 km/hr

We have,

**Online Mock Tests 2019:**