Notes on Percentage | Grade 7 > Compulsory Maths > Percentage | KULLABS.COM

Percentage

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Percent

source: igcseatmathematicsrealm.blogspot.com Fig: Percentage
source: igcseatmathematicsrealm.blogspot.com Fig: Percentage

Percent means parts per hundred or out of hundred. The symbol of a percent is %.

For example, 25% means 25 per 100 or, \(\frac{25}{100}\)

Percentage is a fraction written with a denominator 100.

Conversion of fraction or decimal into percent

source: nzmaths.co.nz Fig: Fraction or Demiacal into Percent
source: nzmaths.co.nz
Fig: Fraction or Decimal into Percent

For the conversion of a fraction or decimal into percent multiply it by 100 and put the symbol % to the product. For example,

\(\frac{2}{5}\) =\(\frac{2}{5}\) × 100 % = 40 %

0.3 = 0.3× 100 % = 30 %

Conversion of percent into fraction or decimal

For the conversion of percent into fraction or decimal, divide it by 100 and remove the % symbol. For example,

20% =\(\frac{20}{100}\) =\(\frac{1}{5}\)

32% =\(\frac{32}{100}\) = 0.32

To express a given quantity as the percent of whole quantity

For the expression of the given quantity as the fraction of the whole quantity, then multiply the fraction by 100%. For examples,

20 as the percent of 80 =\(\frac{20}{80}\) × 100 = 25%

To find the value of given percent of a quantity

If this case is given, then multiply the quantity by the given percent. Then, convert the percent into a fraction and simplify. For example,

25% of Rs.250 = 25%× 250 =\(\frac{25}{100}\)× 250 = Rs. 62.5 ans.

To find a quantity whose value of certain percent is given

If this case is given, we can suppose the whole quantity by a variable such as x. Then we can form an equation and by solving the equation we can find the value of x. For example,

If 20% of a sum is Rs. 80. Find the sum

Here, Let the sum be Rs.x

Now, 20% of x = Rs.80

or, \(\frac{20}{100}\)× x = Rs. 80

or, \(\frac{x}{5}\) = Rs.80

or, x =Rs. 80 × 5 = Rs.400



  • Percentage is a fraction written with a denominator 100.
  • For the conversion of a fraction or decimal into percent multiply it by 100 and put the symbol % to the product. 
  • For the conversion of percent into fraction or decimal, divide it by 100 and remove the % symbol. 
.

Very Short Questions

Solution:

Here, 
the initial rate of a price = Rs 50 per liter
The new rate of a price = rs 55 per liter
∴ Increment in the rate price = Rs 55 - Rs  50 = rs 5
Now,
the increment percentage = \(\frac{Increment \; price}{Initial \; price}\) × 100%
= \(\frac{Rs \; 5}{Rs \; 50}\) × 100% 
= 10%
So, the rate of a price of petrol is increased by 10%

Solution:

Let, the total number of students in the school be x.
Here,
or, 75% of x = 225
or, \(\frac{75}{100}\) × x = 225
or, \(\frac{3x}{4}\) = 225
or, x = \(\frac{4 × 225}{3}\) 
or, x = 300
So, the total number of students in the school is 300,
Again, 
Number of girls = 300 - 225 
So, there are 75 girls in the school.

0%
  • Sameer obtained 60 marks out of 80 full marks in Maths. Express his marks in percentage.

    70%
    75%
    65%
    80%
  • Express (frac{7}{20}) in percentage.

    33%
    39%
    37%
    35%
  • Express 0.48 in percentage.

    4.8%
    8.4%
    84%
    48%
  • Express 56% in decimal.

    5.06
     0.56
    5.6
    05.6
  • Express the Rs 36 as a percentage of Rs 720.

    20%
    10%
    15%
    5%
  • Find the value of 75% of 60 full marks.

    55
    50
    45
    60
  • Find the quantity whose 10% is Rs 160.

    Rs 16.00
    Rs 6000
    Rs 1600
    Rs 16,000
  • (frac{3}{4}) of the total number of students in a school are boys. Find the percentage of boys.

    60%
    70%
    80%
    75%
  • There are 48 students in a class. If 36 of them are boys, find the percentage of boys.

    60%
    75%
    80%
    90%
  • 52% of the total students in a school are girls. If there are 130 girls, find the total number of students in a school.

    270
    290
    250
    230
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