Percentages (Copy)
Practice Questions — 1.13 Percentages
Question 1
Find:
(a) 25% of 240
(b) 12% of 560
(c) 8% of 3200
Question 2
Out of 480 students, 336 are girls.
What percentage of the students are girls?
Question 3
A laptop originally costing Rs. 85 000 is sold at a discount of 12%.
Find the selling price.
Question 4
The population of a town increases from 24 000 to 25 200.
Find the percentage increase.
Question 5
The price of a car decreases from Rs. 2 400 000 to Rs. 2 100 000.
Find the percentage decrease.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
Question 6
A bank pays 5% simple interest per year.
Find the interest on Rs. 40 000 for 3 years.
Question 7
A bank pays 8% compound interest per year.
Find the total amount after 2 years if Rs. 50 000 is invested.
Question 8
A jacket costs Rs. 720 after a discount of 20%.
Find the original price of the jacket.
Question 9
An article is bought for Rs. 15 000 and sold for Rs. 18 000.
Find:
(a) profit
(b) profit percentage.
Question 10
The salary of an employee is increased by 12% to Rs. 67 200.
Find the original salary.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
Question 11
The value of a car decreases by 15% each year.
If the present value is Rs. 1 200 000, find its value after 2 years.
Question 12
A shopkeeper marks goods at 30% above cost price.
He allows a discount of 10% on the marked price.
Find his percentage profit.
Question 13
A sum of Rs. 80 000 is invested for 3 years at 10% compound interest per year.
Find the total amount at the end of 3 years.
Question 14
The price of a mobile phone is increased by 18% and then decreased by 10%.
Find the overall percentage change.
Question 15
In a college, 420 out of 600 students passed an exam.
Find the percentage pass rate.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
Answer key and explanations — 1.13 Percentages
1.
(a) 25% of 240 = (25/100) × 240 = 60
(b) 12% of 560 = (12/100) × 560 = 67.2
(c) 8% of 3200 = (8/100) × 3200 = 256
Explanation: To find a percentage of a number, multiply by (percentage ÷ 100).
2.
336 ÷ 480 × 100 = 70%
Explanation: Express one quantity as a percentage of another by (part ÷ whole × 100).
3.
Discount = 12% of 85 000 = (12/100) × 85 000 = 10 200
Selling price = 85 000 − 10 200 = Rs. 74 800
4.
Increase = 25 200 − 24 000 = 1200
Percentage increase = 1200 ÷ 24 000 × 100 = 5%
5.
Decrease = 2 400 000 − 2 100 000 = 300 000
Percentage decrease = 300 000 ÷ 2 400 000 × 100 = 12.5%
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
6.
Simple interest = P × R × T ÷ 100
= 40 000 × 5 × 3 ÷ 100 = Rs. 6000
7.
Compound interest: A = P(1 + r/100)ⁿ
= 50 000(1 + 8/100)² = 50 000(1.08)²
= 50 000 × 1.1664 = Rs. 58 320
Total = Rs. 58 320
8.
720 = 80% of original price
Original price = 720 ÷ 0.8 = Rs. 900
9.
Cost price = Rs. 15 000, Selling price = Rs. 18 000
(a) Profit = 18 000 − 15 000 = Rs. 3000
(b) Profit % = (3000 ÷ 15 000) × 100 = 20%
10.
New salary = 67 200, increased by 12%
Original = 67 200 ÷ 1.12 = Rs. 60 000
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
11.
Value after 1 year = 1 200 000 × 0.85 = 1 020 000
After 2 years = 1 020 000 × 0.85 = Rs. 867 000
12.
Cost = 100, Marked = 130 (30% more)
Discount 10% → Selling = 130 × 0.9 = 117
Profit = 117 − 100 = 17%
13.
A = 80 000(1.1)³ = 80 000 × 1.331 = Rs. 106 480
14.
Increase 18% → multiply by 1.18
Then decrease 10% → multiply by 0.9
Net factor = 1.18 × 0.9 = 1.062 → 6.2% increase
15.
420 ÷ 600 × 100 = 70% pass rate
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course