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0580/22 Oct/Nov 2025, Question 10: Estimation

Cambridge IGCSE Mathematics 0580 · Paper 22 (Extended) · Non-calculator · 5 marks

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The question, in short

Given b = dm + 2mk, use rounded values of d, m and k to estimate b, then change the formula so m is isolated.

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Part (a) · 3 marks

With d = 3.14, m = 7.92 and k = 10.16, round each to 1 significant figure and calculate an approximate value of b.

  1. 1d ≈ 3, m ≈ 8, k ≈ 10
  2. 2b ≈ 3 × 8 + 2 × 8 × 10 = 24 + 160
  3. 3= 184

Answer184

Part (b) · 2 marks

Rearrange b = dm + 2mk so that m becomes the subject.

  1. 1Start from b = dm + 2mk.
  2. 2Take out the common factor m: b = m(d + 2k)
  3. 3Divide both sides by (d + 2k): m = b/(d + 2k)

Answerb/(d + 2k)

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Also searched as: 0580/22/O/N/25 · 0580_w25_qp_22 · 0580 w25 22 · question 10.
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