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About Percentages & Proportional Reasoning — Class 7 IB

Calculate percentages, discounts, and markups; solve proportional reasoning problems. This topic is part of the IB Class 7 mathematics syllabus (chapter: Unit 2). On this page you can practice 50 questions across three difficulty levels — 10 easy, 20 medium, and 20 hard — each with a visual step-by-step solution, plus a timed 35-question mastery test with a live leaderboard. Worked examples and sample questions from the topic are below.

What you'll learn in Percentages & Proportional Reasoning

  • Introduction to Percentages
  • Calculating Percentages of Quantities
  • Percentage Increase and Decrease
  • Proportional Reasoning: Unitary Method
  • Direct Proportion

Interactive lesson · about 75 minutes · checkpoint question after every unit

Percentages & Proportional Reasoning — solved examples for Class 7 IB

Example 1easy

A souvenir shop bought a sculpture for €120 and sold it for €150. What was the percentage profit for the shop?
  1. A)A. 20%
  2. B)B. 25%
  3. C)C. 30%
  4. D)D. 35%

Step-by-step solution

  1. Calculate the profit: Profit = Selling Price - Cost Price.
    Profit=150120=30Profit = €150 - €120 = €30
  2. Calculate the percentage profit: (Profit / Cost Price) × 100%.
    PercentageProfit=(30/120)×100Percentage Profit = (€30 / €120) × 100% = (1/4) × 100% = 25%

Answer: B. 25%

Example 2medium

The population of Reykjavik was 130 000 in 2018. By 2023, it increased to 139 100. What was the percentage increase in population?
  1. A)5%
  2. B)6%
  3. C)7%
  4. D)8%

Step-by-step solution

  1. Calculate the actual increase in population: New Population - Original Population.
    139100130000=9100139 100 - 130 000 = 9 100
  2. Calculate the percentage increase using the formula: (Increase / Original Population) × 100%.
    (9100/130000)×100(9 100 / 130 000) × 100% = 0.07 × 100% = 7%

Answer: 7%

Example 3hard

The population of a small town in Switzerland increased by 15% over a decade. If the current population is 27 600 people, what was the population a decade ago?
  1. A)23 900
  2. B)24 000
  3. C)24 200
  4. D)24 500

Step-by-step solution

  1. Let the original population be P. An increase of 15% means the current population is 100% + 15% = 115% of the original population.
    Currentpopulation=P×(1+0.15)Current population = P × (1 + 0.15)
  2. So, 27 600 = P × 1.15.
    P=27600÷1.15P = 27 600 ÷ 1.15
  3. Calculating the value gives the original population.
    P=24000P = 24 000

Answer: 24 000

Practice questions on Percentages & Proportional Reasoning

  1. Q1.easy

    A new smartphone is advertised for $960, which includes a 20% VAT (Value Added Tax). What was the original price of the smartphone before the VAT was added?
    1. A)A. $768
    2. B)B. $800
    3. C)C. $720
    4. D)D. $900
    Show answer

    Answer: B. $800

    Hint: If the price includes 20% VAT, the advertised price represents 120% of the original price.

  2. Q2.easy

    If 7 identical books cost £56, how much would 12 of these books cost?
    1. A)A. £84
    2. B)B. £96
    3. C)C. £108
    4. D)D. £112
    Show answer

    Answer: B. £96

    Hint: Find the cost of one book first. This is a common strategy in 'unitary method' problems.

  3. Q3.easy

    A car travels 210 km in 3 hours at a constant speed. How far will it travel in 5 hours at the same speed?
    1. A)A. 300 km
    2. B)B. 320 km
    3. C)C. 350 km
    4. D)D. 380 km
    Show answer

    Answer: C. 350 km

    Hint: Since the speed is constant, distance and time are directly proportional. Find the speed (km per hour) first.

  4. Q4.medium

    A new drone was priced at €350. During a holiday sale, its price dropped to €297.50. What was the percentage decrease in the drone's price?
    1. A)10%
    2. B)15%
    3. C)20%
    4. D)25%
    Show answer

    Answer: 15%

    Hint: Find the amount of the price drop first, then calculate what percentage that drop is of the original price.

  5. Q5.medium

    A jacket in a London boutique has an original price of £80. If there's a 25% discount, how much will a customer pay for the jacket?
    1. A)£60
    2. B)£65
    3. C)£70
    4. D)£75
    Show answer

    Answer: £60

    Hint: You can either calculate the discount amount and subtract it, or directly calculate the percentage of the original price that remains after the discount.

  6. Q6.medium

    A small café buys coffee beans for $15 per kilogram. To cover costs and make a profit, they mark up the price by 60%. What is the selling price per kilogram of coffee beans?
    1. A)$21
    2. B)$22.50
    3. C)$23
    4. D)$24
    Show answer

    Answer: $24

    Hint: Calculate the amount of the markup, then add it to the original cost price to find the selling price.

  7. Q7.hard

    A rare species of bird saw its population decrease by 20% due to habitat loss. The current population is 1600 birds. Alex calculated the original population by adding 20% to 1600, reaching 1920 birds. What was Alex's mistake?
    1. A)He should have subtracted 20% from 1600.
    2. B)He incorrectly assumed the 20% decrease was based on the current population.
    3. C)The 20% decrease should have been calculated from the original population, not the current population.
    4. D)He calculated the percentage change incorrectly, it should be a fraction.
    Show answer

    Answer: The 20% decrease should have been calculated from the original population, not the current population.

    Hint: The percentage decrease always refers to a percentage of the *original* amount. Consider what percentage of the original population 1600 represents.

  8. Q8.hard

    A designer backpack originally priced at €250 in Paris is on sale with a 20% discount. After the discount, a Value Added Tax (VAT) of 15% is applied to the discounted price. What is the final price of the backpack?
    1. A)€210.00
    2. B)€220.00
    3. C)€230.00
    4. D)€237.50
    Show answer

    Answer: €230.00

    Hint: Remember to apply the discount first, and then calculate the VAT on the new, discounted price. Order of operations matters in multi-step percentage problems.

  9. Q9.hard

    During a flash sale, a smart tablet was sold for $340 after a 15% discount. What was the original price of the tablet before the discount?
    1. A)$380
    2. B)$390
    3. C)$400
    4. D)$410
    Show answer

    Answer: $400

    Hint: If an item is sold at a 15% discount, the selling price represents 100% - 15% of the original price. Use this to work backwards.

These are 9 of the 50 questions available for Percentages & Proportional Reasoning. Start practicing above to unlock visual solutions, AI coaching, and the topic leaderboard — completely free.