Easy method for Boats and Streams

Today i am going to discuss about Boats and streams problems. Observe the below image and note down in your paper as 3 different pictures. Then those are enough to answer any type of BOATS AND STREAMS problem. So, lets see how it works. First of all, see those three vertical broad lines. They denotes Up stream, Speed in still water, and Down stream. And the two small ones are both same, they are stream speeds. When you want to solve this boats problem, draw these lines and mention their appropriate numbers, given in the problem.

Now, we will take an example problem, to solve.

A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream.

 

now, we will take another example to solve in this method.

In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:
Sol : You can see the difference between up(against) and Down (along or with)is 11-5 =6
as we have 2 stream speed lines, 6/2 = 3kmph is the stream speed.
now, subtract 3 from 11 or add 3 to 5 which implies 8 anyways.
hence still water speed is 8kmph.

This may take a while to remember. But with this it is easy to minimize time in our examinations.

NOTE : Here is a note to mention. When the arrow going to down stream, it is a plus. ie you need to add when it is down arrow. And Up arrow.. minus

 If you may find difficult to remember plus or minus sequence, one small hint is there. Always up stream is lesser than down stream. UP < DOWN

Here i am giving you some problems. Try solving it out.


1. A motorboat, whose speed in 15 km/hr in still water goes 30 km downstream and comes back in a total of 4 hours 30 minutes. What is the speed of the stream (in km/hr)

2. A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is?

3. 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?

4. A boat covers a certain distance downstream in 1 hour, while it comes back in 1 hours. If the speed of the stream be 3 kmph, what is the speed of the boat in still water?

5. A man rows to a place 48 km distant and come back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is?

6. A man can row at 5 kmph in still water. If the velocity of current is 1 kmph and it takes him 1 hour to row to a place and come back, how far is the place?

7. The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance traveled downstream in 12 minutes is?



Hope this is useful to you and understood. If there is any doubts, pls find time to post me. I'll try my best to answer you. And also if you find any mistakes, make a note of it too. :) see you

RBI computer awareness solved questions

Question 1: In an excel worksheet, the intersection of a row and a column is called ?

1. Column
2. Value
3. Address

4. Cell

5.

Correct Answer: 4.


Question 2: Translation and execution of a program line by line at run time is performed by which of the following?

1. Compiler
2. Interpreter
3. Linker
4. Loader
5.

Correct Answer: 2.


Question 3: In EXCEL, a workbook contains ______ worksheets by default.

1. One worksheet
2. Two worksheets
3. Three worksheets
4. Four worksheets
5.

Correct Answer: 3.


Question 4: How many number of address lines are required for 1 MB memory

1. 11
2. 16
3. 22
4. 24
5.

Correct Answer: 2.


Question 5: A linked list is an example of a _______ data structure

1. Linear
2. Non-Linear
3. Static
4. Dynamic
5.

Correct Answer: 4.


Question 6: Which key is used to switch to the full screen view while browsing the internet ?

1. F3
2. F5
3. F11
4. F9
5. F10

Correct Answer: 3.


Question 7: MS-Excel considers any set of characters containing a letter , hyphen, or space as _______

1. a formula
2. text
3. a name
4. a title
5.

Correct Answer: 2.


Question 8: Data can be sent over a serial communication link layer using a minimum of _____ wires

1. 1
2. 2
3. 4
4. 6
5.

Correct Answer: 2.


Question 9: Which function key is used to display "save as" box ?

1. F5
2. F6
3. F9
4. F12
5.

Correct Answer: 4.


Question 10: A number system with a base of two is referred as?

1. Octal number system
2. Unary number system
3. Binary number system
4. None of these
5.

Correct Answer: 3.


Question 11: A broad band communication channel can be considered as which of the following?

1. coaxial cable
2. fiber optics cable
3. microwave circuits
4. All of the above
5.

Correct Answer: 4.


Question 12: XSL stands for

1. Extensible Symmetric Language
2. Extensible Stylesheet Language
3. Extendible Symmetric Language
4. Extendible Stylesheet Language
5.

Correct Answer: 2.


Question 13: Which key combination is used to Change text to heading 3

1. Ctrl + 3
2. Alt + 3 
3. Alt + Ctrl + h3 
4. Ctrl + Alt + 3 
5.

Correct Answer: 4.


Question 14: What is an applet ?

1. is a compiled program that usually runs on the client
2. collects data from visitors to a Website
3. tracks the number of visitors to a Website
4. is an interpreted program that runs on the client
5. None of these

Correct Answer: 1.


Question 15: Which device used by Internet Service Providers to route incoming DSL connections to the Internet ?

1. Router
2. DSLAM
3. NIC Card
4. MODEM
5.

Correct Answer: 2.


Question 16: A program used to browse the web is called _______.

1. internet
2. browser
3. HTML
4. website
5.

Correct Answer: 2.


Question 17: The binary equivalent of the octal number 237 is _______

1. 010 011 111
2. 010 111 011
3. 011 101 101
4. 011 000 001
5.

Correct Answer: 3.


Question 18: What was the switching device used in the first generation computers ?

1. VLSI
2. Integrated Circuits
3. Germanium Transistors
4. Vaccuum Tubes
5.

Correct Answer: 4.


Question 19: Which of the following refers to a small, single-site network ?

1. DSL
2. RAM
3. USB
4. CPU
5. LAN

Correct Answer: 5.


Question 20: Third normal form is inadequate in situations where the relation

1. Has does not multiple candidate keys
2. Has candidate keys that are not composite
3. Has overlapped candidate keys
4. None of the above
5.

Correct Answer: 3.


Question 21: A system has 3 processes sharing 4 resources. If each process needs a maximum of 2 units then

1. deadlock may occur
2. deadlock can never occur
3. deadlock has to occur
4. None of these
5.

Correct Answer: 2.


Question 22: The name given to something that the computer will automatically do unless you specify otherwise?

1. a specification
2. a wildcard
3. a default
4. a rule 
5.

Correct Answer: 3.


Question 23: Softwares with malicious intent, such as viruses, worms and Trojan horses are known as ______

1. spyware
2. adware
3. spam
4. malware
5.

Correct Answer: 4.


Question 24: The computer program that are most commonly used are likely to be retrived from -

1. Cache memory
2. RAM
3. Registers
4. CDs
5.

Correct Answer: 1.


Question 25: Which shortcut key is used to delete cells, rows or columns?

1. CTRL+ Minus Sign
2. CTRL+ Plus Sign
3. CTRL+ Star Sign
4. CTRL+ Greater than Sign
5.

Correct Answer: 1.

Percantage change Or Profit-loss

1. The price of petrol is increased by 25%. By what percent the consumption be reduced to make the expenditure remain the same?

a. 25%             b. 33.33%                    c. 20%             d. None

2. If the length of a rectangle is increased by 33.33%, by what percentage should the breadth be reduced to make the area same?

a. 20%             b. 33.33%                    c. 25%             d. None

Have the below list::::::::::::::::

  

10%                            0.1                               1/10

12.5%                         0.125                           1/8

16.66%                       0.1666                         1/6

20%                            0.2                               1/5

25%                            0.25                             1/4

30%                            0.3                               3/10

33.33%                       0.3333                         1/3

40%                            0.4                               2/5

50%                            0.5                               1/2

60%                            0.6                               3/5

62.5%                         0.625                           5/8

66.66%                       0.6666                         2/3

70%                            0.7                               7/10

75%                            0.75                             3/4

80%                            0.8                               4/5

83.33%                       0.8333                         5/6

90%                            0.9                               9/10

100%                          1.0                                1

Short trick for above problems:

in first problem,he want to bring back the original value,so need to decrease the value.

price increased,so became–25%

in the above list,see the next decreased value from 25% IS 20% so yopur answer is 20%

in second problem

increased value——–33.33%

next decreased value–30%,SO ANSWER IS 30%

Percentage Change:

A change can be of two types – an increase or a decrease.                    

When a value is changed from initial value to a final value,

% change = (Difference between initial and final value/initial value) X 100

Eg: If 20 changes to 40, what is the % increase?

Soln: % increase = (40-20)/20 X 100 = 100%.

Note:

1. If a value is doubled the percentage increase is 100.

2. If a value is tripled, the percentage change is 200 and so on.

Percentage Difference:

% Difference = (Difference between values/value compared with) X 100.

Eg: By what percent is 40 more than 30?

Soln: % difference = (40-30)/30 X 100 = 33.33%

(Here 40 is compared with 30. So 30 is taken as denominator)

Eg: By what % is 60 more than 30?

Soln: % difference = (60-30)/30 X 100 = 100%.

(Here is 60 is compared with 30.)

Hint: To calculate percentage difference the value that occurs after the word “than” in the question can directly be used as the denominator in the formula.

Understanding Profit and Loss:

So, by now we came to know that if CP is increased and sold it would result in profit and vice versa.

Also whatever increase is applied to CP, that increase itself is the profit.

For Rs. 10 profit, CP is to be increased by RS. 10 and the increased price becomes SP.

For 10% profit, CP is to be increased by 10% and it is the SP.

(From previous chapter we know that any value increased by 10% becomes 1.1 times.)

So, for 10% profit, CP increased by 10% => 1.1CP = SP.

·        SP = 1.1CP => SP/CP = 1.1 => 10% profit

·        SP = 1.07CP => SP/CP = 1.07 => 7% profit

·        SP = 1.545CP => SP/CP = 1.545 => 54.5% profit and so on.

Similarly,

·        SP = 0.9CP => SP/CP = 0.9 => 10% loss (Since 10% decrease)

·        SP = 0.76CP => SP/CP = 0.76 => 24% loss and so on.

So, to calculate profit % or loss %, it is enough for us to find the ratio of SP to CP.

Note:

1.      If SP/CP > 1, it indicates profit.

2.      If SP/CP < 1, it indicates loss.

Multiple Profits or losses:

A trader may sometimes have multiple profits or losses simultaneously. This is equivalent to having multiple changes and so all individual changes are to be multiplied to get the overall effect.

Relationship among CP, SP and MP:

A trader adds his profit to the investment and sells it at that increased price.

Also he allows a discount on Marked Price and sells at the discounted price.

So, we can say that,

SP = CP + Profit. (CP applied with profit is SP)

SP = MP – Discount. (MP applied with discount is SP)

Q: A trader uses 1 kg weight for 800 gm and increases the price by 20%. Find his profit/loss %.

Soln: 1 kg weight for 800 gm => loss (decrease) => 800/1000 = 0.8

20% increase in price => profit (increase) => 1.2

So, net effect = (0.8) X (1.2) = 0.96 => 4% loss.

2.      A milk vendor mixes water to milk such that he gains 25%. Find the percentage of water in the mixture.

Soln: To gain 25%, the volume has to be increased by 25%.

So, for 1 lt of milk, 0.25 lt of water is added => total volume = 1.25 lt

% of water = 0.25 / 1.25 X 100 = 20%.