Percentage is used to represent as a fraction of something over 100. (per cent)means per 100 and at the back of every percentage there is always this sign,%.
For example,55% when converted to fraction it would be 55/100 . Since percentage means a fraction of something over 100,just put the percent/100 when converting percentage to fraction. Same goes for decimal. 1.00=100%.When converting percentage to decimal just put the percentage behind "0.".
These are some examples:
I have 100 marbles and you have 200. If you want to express your marbles as a percentage of mine, the formula is
(no. of your marbles/ no. of my marbles) x 100%
but if it is expressing mine as a percentage of yours it will be
(no. of my marbles/no. of your marbles) x 100%
Let’s say that I have 50% of the stocks in this market and it decreased by 20%. The percentage of remaining sticks is not 50%-20%.It is 20/100 X 50%.
It works the same way as fraction. If I have half of the stocks then it decreased by 1/5, it is not ½ -1/5 . If it is decreased by 1/5 it should be left with 4/5 so the answer should be 4/5 x ½.
For percentage, it would be the percentage left/100 x original amount. It is the same for increase.
If there is a sale and it offers 10% discount and another 20% discount for member do not be fooled and sign up as a member. It may seem to you as 10% + 20% and a total of 30% discount but it is wrong. It’s actually 100% - 10% then 20/100 X 90% which is 28% in total not 30%.
Monday, March 23, 2009
Interest
Simple Interest
To put it in simple term simple interest is a interest that is charged on the original amount,on that portion of the original amount which remains unpaid.
For example:
A bank gives a 5% simple interest at the end of the year. If i put $1000 in the bank for 2 years, how much will there be at the end of the 2 years?
5% x 1000 = $50 dollars
$1000 + $50 = $1050 (at the end of first year)
$1050 + $50 = $1100 (at the end of 2nd year)
There will be $1100 at the end of 2 years.
**Notice that the 5% interest for the second year is charged on the original amount, $1000, and not the amount of money at the end of the first year, $1050.
Compound Interest
Compound interest is very similar to simple interest; however, with time, the difference becomes considerably larger. This difference is because unpaid interest is added to the balance due. Put another way, the borrower is charged interest on previous interest.
Using the same question as an example:
A bank gives 5% compound interest at the end of the year. If i put $1000 in the bank for 2 years, how much will there be at the end of 2 years?
5% x $1000 = $50
$1000 + $50 = $1050 (at the end of 1 year)
5% x $1050 = 52.5
$1050 + $52.50 = $1102.5 (at the end of 2 years)
There will be $1102.50 at the end of 2 years.
**Notice that the 5% interest for the second year is charged on the final sum of money at the end of the first year, $1050 and not the amount of money at the start of the first year, $1000.
Some things that might use compound or simple interest would be:
1. Bank interest
2. Buying things with installments, with interest charged.
3. Buying insurance
and so on.
Sources:
http://en.wikipedia.org/wiki/Interest
To put it in simple term simple interest is a interest that is charged on the original amount,on that portion of the original amount which remains unpaid.
For example:
A bank gives a 5% simple interest at the end of the year. If i put $1000 in the bank for 2 years, how much will there be at the end of the 2 years?
5% x 1000 = $50 dollars
$1000 + $50 = $1050 (at the end of first year)
$1050 + $50 = $1100 (at the end of 2nd year)
There will be $1100 at the end of 2 years.
**Notice that the 5% interest for the second year is charged on the original amount, $1000, and not the amount of money at the end of the first year, $1050.
Compound Interest
Compound interest is very similar to simple interest; however, with time, the difference becomes considerably larger. This difference is because unpaid interest is added to the balance due. Put another way, the borrower is charged interest on previous interest.
Using the same question as an example:
A bank gives 5% compound interest at the end of the year. If i put $1000 in the bank for 2 years, how much will there be at the end of 2 years?
5% x $1000 = $50
$1000 + $50 = $1050 (at the end of 1 year)
5% x $1050 = 52.5
$1050 + $52.50 = $1102.5 (at the end of 2 years)
There will be $1102.50 at the end of 2 years.
**Notice that the 5% interest for the second year is charged on the final sum of money at the end of the first year, $1050 and not the amount of money at the start of the first year, $1000.
Some things that might use compound or simple interest would be:
1. Bank interest
2. Buying things with installments, with interest charged.
3. Buying insurance
and so on.
Sources:
http://en.wikipedia.org/wiki/Interest
Speed
Speed
Speed is literally, the rate whereby an object is moving at.
The formula to find speed is:
Speed = Distance / Time (Distance or time being the constant)
Likewise, the formula to find time and distance would be as follows:
Distance = Speed x Time (Speed or time being the constant)
Time = Distance / Speed ( Distance and speed being the constant)
The term uniform speed means the speed of a body that is constant over a certain period of time.
In many situations, objects do not move at a constant speed. For example, if a car goes 60 miles in 2 hours, its average speed during that time is 30 miles per hour, but its instantaneous speed may have varied.
Average Speed
When you need to find the average speed of a body, it means that the body had most probably travelled a particular distance over a particular time at different speed.
The following is the formula for finding average speed:
Total distance travelled/ Total time taken (for whole journey)
Sources:
http://en.wikipedia.org/wiki/Speed
Speed is literally, the rate whereby an object is moving at.
The formula to find speed is:
Speed = Distance / Time (Distance or time being the constant)
Likewise, the formula to find time and distance would be as follows:
Distance = Speed x Time (Speed or time being the constant)
Time = Distance / Speed ( Distance and speed being the constant)
The term uniform speed means the speed of a body that is constant over a certain period of time.
In many situations, objects do not move at a constant speed. For example, if a car goes 60 miles in 2 hours, its average speed during that time is 30 miles per hour, but its instantaneous speed may have varied.
Average Speed
When you need to find the average speed of a body, it means that the body had most probably travelled a particular distance over a particular time at different speed.
The following is the formula for finding average speed:
Total distance travelled/ Total time taken (for whole journey)
Sources:
http://en.wikipedia.org/wiki/Speed
Concepts of Ratio, rate and direct proportion
Ratio
Ratio is an expression when you compare quantities with each other. The numbers that are separated by the colon are called terms.
The most common form of ratio involves only 2 terms , for example, 4:5. Real life examples would be things like the scores of a sports competition.
A ratio would be read as " x is to y ". For instance, 4:5 would be read as "4 is to 5"
Ratio can be interpreted in 2 ways: (Example would be the ratio 1:5)
1. Quantity of the latter is 5 times of the first quantity
2. The first quantity is 1/5 (one- fifth) of the second one. (meaning, ration can be expressed as a fraction)
Rate
Rate is a ratio between 2 measurements, often with different units. For example, to describe speed, a rate would be 20 km/h. (20 km per hour)
In describing the units of a rate, the word "per" is used to separate the units. Like the previous example given - 20 km per hour.
Direct Proportion
On a graph, a direct proportion would have a positive straight line, since there is no change and it is constant.
An example of direct proportion would be, if an object travels at a constant speed, then the distance traveled is proportional to the time spent travelling, with the speed being the constant of proportionality.
(the constant is the one that will not change throughout the time)
Sources:
http://en.wikipedia.org/wiki/Direct_proportion
http://en.wikipedia.org/wiki/Rate_(mathematics)
http://en.wikipedia.org/wiki/Ratio
Ratio is an expression when you compare quantities with each other. The numbers that are separated by the colon are called terms.
The most common form of ratio involves only 2 terms , for example, 4:5. Real life examples would be things like the scores of a sports competition.
A ratio would be read as " x is to y ". For instance, 4:5 would be read as "4 is to 5"
Ratio can be interpreted in 2 ways: (Example would be the ratio 1:5)
1. Quantity of the latter is 5 times of the first quantity
2. The first quantity is 1/5 (one- fifth) of the second one. (meaning, ration can be expressed as a fraction)
Rate
Rate is a ratio between 2 measurements, often with different units. For example, to describe speed, a rate would be 20 km/h. (20 km per hour)
In describing the units of a rate, the word "per" is used to separate the units. Like the previous example given - 20 km per hour.
Direct Proportion
On a graph, a direct proportion would have a positive straight line, since there is no change and it is constant.
An example of direct proportion would be, if an object travels at a constant speed, then the distance traveled is proportional to the time spent travelling, with the speed being the constant of proportionality.
(the constant is the one that will not change throughout the time)
Sources:
http://en.wikipedia.org/wiki/Direct_proportion
http://en.wikipedia.org/wiki/Rate_(mathematics)
http://en.wikipedia.org/wiki/Ratio
Subscribe to:
Posts (Atom)
