**Most Important Questions of Boat and Streams**

Dear Readers, Welcome to **BOATS AND STREAMS - Aptitude Objective Questions** have been designed specially to get you acquainted with the nature of questions you may encounter during your Job interview for the subject of **BOATS AND STREAMS - Aptitude MCQs**. These objective type **BOATS AND STREAMS - Aptitude questions** are very important for campus placement test and job interviews. As per my experience good interviewers hardly plan to ask any particular question during your Job interview and these model questions are asked in the online technical test and interview of many Banks, SSC, Railways, Postal and many Govt Jobs.

**Formulas of Boats and Streams Questions Answers**

**Formulas:**

**1. In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.**

**2. If the speed of a boat in still water is u km/ht and the speed of the stream is v km/hr, then :**

Speed downstream = (u + v) km/hr

Speed upstream (u - v) km/hr.

**3. If the speed downstream is a km/hr and the speed upstream is b km/hr, then :**

Speed in strill water = 1/2 (a + b) km/hr

Rate of stream = 1/2 (a - b) km/hr

**BOATS AND STREAMS - SOLVED EXAMPLE PROBLEMS**

**1. In a stream running at 2 kmph, a motorboat goes 6 km upstream and back again to the starting point in 33 minutes. Find the speed of the motorboat in still water.**

Explanation: Let the speed of the motorboat in still water be x kmph. Then,

Speed downstream = (x + 2) kmph; Speed upstream = (x - 2) kmph.

? 6/x+2 + 6/x-2 = 33/60

? 11x² - 240x - 44 = 0

? 11x² - 242x + 2x - 44 = 0

? (x - 22) (11x + 2) = 0 ? x = 22.

Hence, speed of motorboat in strill water = 22 kmph.

**2. A man can row 18 kmph in still water. It takes him trice as long to row up as to row down the river. Find the rate of stream.**

Explanation: Let man’s rate upsream be x kmph. Then, his rate downstream = 3x kmph.

? Rate in still water = 1/2(3x + x) kmph = 2x kmph.

So, 2x = 18 or x = 9.

? Rate upstream = 9 km/hr, Rate downstream = 27 km/hr.

Hence, rate of stream = 1/2(27 - 9) km/hr = 9 km/hr.

**3. A man can row upstream at 7 kmph and downstream at 10 kmph. Find man’s rate in still water and the rate of current.**

Explanation: Rate in still water = 1/2 (10 + 7) km/hr = 8.5 km/hr,

Rate of current = 1/2 (10 - 7) km/hr = 1.5 km/hr.

**4. If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph, then the speed of the boat in still water is : . [C.B.I. 1993]**

Explanation:

Rate upstream = (7/42)*60 kmh = 10 kmph. Speed of stream = 3 kmph.

Let speed in sttil water is x km/hr

Then, speed upstream = (x —3) km/hr.

x-3 = 10 or x = 13 kmph.

**5. If a man can swim downstream at 6 kmph and upstream at 2 kmph, his speed in still wateris : **

Explanation:

Speed in still water = (1/2) * (6 + 2) km/hr

= 4 km/hr