hello frndz,
first of all, happy Dhusera to all!!! Today we will learn about percent and its uses....
:- A percent is a number out of 100. For eg. 20% means 20 out of 100.
20% = 20/100 = 0.2
:- To find a certain percent of a number for less than 50%, first calculate 10% by putting decimal after unit digit then calculate accordingly. For greater than more than 50%, first calculate 50% by doing half the number and then calculate remaining one...
For eg. To find 20% of 90;
First calculate 10% and 10% of 90 is 9 (remove unit digit 0).
Now, 20 % is twice of 10% i.e. twice of 9 = 2*9 = 18;
To find 80% of 90;
First calculate 50% i.e. 45 (half of 90)
Now, calculate remaining 30% i.e. thrice of 10% = 3*9 = 27
So 80% of 90 = 45 + 27 = 72
To find 3% of 90;
First calculate 1% by putting decimal after last two digits i.e. 0.90
now, 3% of 90 is thrice of 1% = 3*0.9 = 2.7
:- Percents greater than 100% known as numbers greater than 1.
for eg. 300% means 3 times, 200% means 2 times and 250% means 2.5 times etc....
250% of 80 = 2.5 * 80 = 200
:- Percents less than 1%: The percent 0.5% is half of 1%. For eg. 0.5% of 12 is the half of 1 % of 12 i.e.
1/2 * 0.12 = 0.06;
:- Percent change: For eg. if price of an item increased from $24 to $30, then price increased by $6 on the base price of $24 So percent increase is '$6 is what percent of $24?'
(Short method: half of $24 is $12 that is 50% of $24 and $6 is half of $12, again 50% of $12 So $6 is one forth of $24 i.e. 25% of $24).
So percent increase from $24 to $30 is 25%
Now reverse the question; If price of an item decreased from $30 to $24, then price decreased by $6 on the base price of $30 So percent decrease is '$6 is what percent of $30?'
(Short method: 10% of $30 = 3 and $6 is twice of $3 So $6 is 20% of $30).
So percent decrease from $30 to $24 is 20%
(Note: Percent increase from 24 to 30 is not equal to Percent decrease from 30 to 24).
:- If the cost of a certain house in 1983 was 300% of its cost in 1970, by what percent did the cost increase?
Let assume the cost of a house in 1970 was 100 then cost in 1983 was 300 So increase by 200 on base price of 100 i.e. 200%
Okie guys, Keep practice on !!!
Some good books for GMAT Quant prep:
1. Quant Official guide 12th Edition
2. Kaplan Matrial
3. Nova GMAT
etc..............
Er. Ankur Garg
garg.ankur6@gmail.com
www.nascentedutech.com
first of all, happy Dhusera to all!!! Today we will learn about percent and its uses....
:- A percent is a number out of 100. For eg. 20% means 20 out of 100.
20% = 20/100 = 0.2
:- To find a certain percent of a number for less than 50%, first calculate 10% by putting decimal after unit digit then calculate accordingly. For greater than more than 50%, first calculate 50% by doing half the number and then calculate remaining one...
For eg. To find 20% of 90;
First calculate 10% and 10% of 90 is 9 (remove unit digit 0).
Now, 20 % is twice of 10% i.e. twice of 9 = 2*9 = 18;
To find 80% of 90;
First calculate 50% i.e. 45 (half of 90)
Now, calculate remaining 30% i.e. thrice of 10% = 3*9 = 27
So 80% of 90 = 45 + 27 = 72
To find 3% of 90;
First calculate 1% by putting decimal after last two digits i.e. 0.90
now, 3% of 90 is thrice of 1% = 3*0.9 = 2.7
:- Percents greater than 100% known as numbers greater than 1.
for eg. 300% means 3 times, 200% means 2 times and 250% means 2.5 times etc....
250% of 80 = 2.5 * 80 = 200
:- Percents less than 1%: The percent 0.5% is half of 1%. For eg. 0.5% of 12 is the half of 1 % of 12 i.e.
1/2 * 0.12 = 0.06;
:- Percent change: For eg. if price of an item increased from $24 to $30, then price increased by $6 on the base price of $24 So percent increase is '$6 is what percent of $24?'
(Short method: half of $24 is $12 that is 50% of $24 and $6 is half of $12, again 50% of $12 So $6 is one forth of $24 i.e. 25% of $24).
So percent increase from $24 to $30 is 25%
Now reverse the question; If price of an item decreased from $30 to $24, then price decreased by $6 on the base price of $30 So percent decrease is '$6 is what percent of $30?'
(Short method: 10% of $30 = 3 and $6 is twice of $3 So $6 is 20% of $30).
So percent decrease from $30 to $24 is 20%
(Note: Percent increase from 24 to 30 is not equal to Percent decrease from 30 to 24).
:- If the cost of a certain house in 1983 was 300% of its cost in 1970, by what percent did the cost increase?
Let assume the cost of a house in 1970 was 100 then cost in 1983 was 300 So increase by 200 on base price of 100 i.e. 200%
Okie guys, Keep practice on !!!
Some good books for GMAT Quant prep:
1. Quant Official guide 12th Edition
2. Kaplan Matrial
3. Nova GMAT
etc..............
Er. Ankur Garg
garg.ankur6@gmail.com
www.nascentedutech.com
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