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      Problem solving with further sequences

      Lesson details

      Learning outcome

      I can use my enhanced knowledge of sequences to solve problems.

      Key learning points

      1. Compound interest can be thought of as a geometric sequence.
      2. You can apply your knowledge of geometric sequences to solve compound interest problems.

      Keywords

      • Interest - Interest is money added to savings or loans.

      • Compound interest - Compound interest is calculated on the original amount and the interest accumulated over the previous period.

      • Geometric sequence - A geometric sequence is a sequence with a constant multiplicative relationship between successive terms.

      • Common ratio - In a geometric sequence, the constant multiplier between successive terms is called the common ratio.

      Common misconception

      A multiplier of 1.3 is used to increase a value by 3%

      A multiplier of 1.3 is used to increase a value by 30%

      Teacher tip

      The final question in Task B has a large version of Pascal's triangle on the final page of the worksheet. This could be printed and laminated to allow pupils to investigate shading the triangle without each pupil needing multiple copies of the triangle.

      Licence

      This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      Interest which is calculated on the original amount and the interest accumulated over the previous period is called __________ interest.

      average
      Correct answer: compound
      linear
      repeated
      simple

      Q2.
      Match the type of sequence with its description.

      Correct Answer:Arithmetic,a sequence with a common difference between successive terms.

      a sequence with a common difference between successive terms.

      Correct Answer:Fibonacci,a sequence where each term is the sum of the two previous terms.

      a sequence where each term is the sum of the two previous terms.

      Correct Answer:Geometric,a sequence with a common multiplier between successive terms.

      a sequence with a common multiplier between successive terms.

      Correct Answer:Quadratic (e.g. square numbers),a sequence with a common second difference.

      a sequence with a common second difference.

      Q3.
      Which of these could be the first 5 terms in an arithmetic sequence?

      Correct answer: 1, 2, 3, 4, 5, ...
      1, 2, 4, 8, 16, ...
      Correct answer: 8, 11, 14, 17, 20, ...
      15, 18, 22, 24, ...
      16, 40, 100, 250, 375, ...

      Q4.
      Which of these could be the first 5 terms in a geometric sequence?

      Correct answer: 1, 2, 4, 8, 16, ...
      1, 4, 16, 36, 64, ...
      3, 5, 8, 12, 20, ...
      Correct answer: 4, 20, 100, 500, 2500, ...
      5, 10, 15, 20, 25, ...

      Q5.
      If a geometric sequence starts 20, 60, 180, ... what is the common ratio (common multiplier)?

      Correct Answer: 3

      Q6.
      If a geometric sequence starts 50, 60, 72, ... what is the common ratio? Give your answer as a decimal.

      Correct Answer: 1.2

      6 Questions

      Q1.
      What type of sequence has been shaded on Pascal's triangle?

      An image in a quiz
      An alternating sequence
      Correct answer: An arithmetic sequence
      A Fibonacci sequence
      A geometric sequence
      A quadratic sequence (sequence with common second difference)

      Q2.
      Which of these best describes the sequence of numbers shaded on Pascal's triangle?

      An image in a quiz
      An arithmetic sequence
      A geometric sequence
      The sequence of all cube numbers
      The sequence of all square numbers
      Correct answer: The sequence of all triangular numbers

      Q3.
      £24 000 is borrowed at a compound interest rate of 5% a month. How much is owed after 3 months?

      Correct Answer: £27 783, £27783, 27783, 27 783

      Q4.
      £800 is borrowed with yearly compound interest and after a year £1040 is owed. What is the yearly interest rate?

      1.3%
      13%
      25%
      Correct answer: 30%
      40%

      Q5.
      A loans company charges 6% interest a month. If £2650 was owed after one month, how much was borrowed?

      Correct Answer: £2500, 2500, 2 500, £2 500

      Q6.
      £750 was borrowed with compound interest and after 2 years making no repayments £1080 was owed. What was the yearly interest rate?

      6.6%
      18%
      Correct answer: 20%
      44%
      72%

      To help you plan your 11 maths lesson on: Problem solving with further sequences, download all teaching resources for free and adapt to suit your pupils' needs...