Basic Percentage Questions

A percentage is a way of expressing a number as a fraction of 100. It is represented by the symbol %.

For example, 25% means 25 out of 100, or: 25\% = \frac{25}{100} = \frac{1}{4}

Solved Example

Example 1: Find 15 % of 500.

Solution:

We can find the percentage by formula, 

V₂ = P × V₁
⇒ V₂ = 15% × 500
⇒ V₂ = (15 × 500) / 100 
⇒ V₂ = 75.

Thus, 15% of 500 is 75.

Example 2: What percentage is 1 of 3000?

Solution:

We can find the percentage by formula,

V₂ = P × V₁
⇒ P = V₂ / V₁
⇒ P = 1 / 3000

Thus, P% = 1/3000 × 100
⇒ P% = (1/30)%

Thus, 1 is 0.03333% of 3000.

Example 3: If 10% of x is 900. Find x.

Solution:

We can find the percentage by the formula,

V₂ = P × V₁
⇒ V₁ = V₂ / P
⇒ V₁ = (V₂ × 100 ) / P%
⇒ V₁ = (900 × 100) / 10
⇒ V₁ = 9000

Thus, the value of x is 9000.

Example 4: Find the value of the percentage of green blocks in each case.

Solution:

• In first case, the green blocks are 0, and the total blocks are 36. 
  Therefore, Percentage of green Blocks = 0/36 × 100 = 0%.

• In second case, the green blocks are 18, and the total blocks are 36. 
  Therefore, Percentage of green Blocks = 18/36 × 100 = 50%.

• In third case, the green blocks are 27 and the total bricks are 36. 
  Therefore, Percentage of green Blocks = 27/36 × 100 = 75%.

Example 5: A student scored 72 marks out of 90. Find the percentage.

Solution : Percentage = Total Marks obtained / Total Marks ​× 100

=\frac{72}{90}\times100 = 80%

Example 6: The price of a book is ₹800. It is sold at a 15% discount. Find the selling price.

Solution:

Discount:

15% of 800 = \frac{15}{100}\times800 = 120

Selling Price: 800 - 120 = 680

Example 7: Find 30% of 200.

Solution:

30% of 200 = 30/100 ✖ 200 = 60

Example 8: A student scored 40 marks out of 50. Find the percentage.

Solution:

Percentage=40/50 ​× 100 = 80%

Practice Questions:

Q1. Find 5% of 200.

Q2. Find 15% of 100.

Q3. Find 25% of 120.

Q4. Find 40% of 150.

Q5. Find 75% of 80.

Q6. 20 is what percentage of 100.

Q7. 15 is what percentage of 60.

Q8. A student scored 45 marks out of 50. Find the percentage.

Q9. A box contains 200 apples. If 10% are rotten, how many apples are rotten.

Q10. A shirt costs ₹800. Find 20% of its price.