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4024/12 May/Jun 2022, Question 12: Estimation

Cambridge O Level Mathematics 4024 · Paper 12 (Non-calculator) · Non-calculator · 3 marks

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The question, in short

Round 0.002 035 61 to 3 significant figures, then estimate (√3.93 × 63.7) ÷ 0.425 by rounding each number to 1 significant figure.

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Part (a) · 1 mark

Give 0.002 035 61 rounded to 3 significant figures.

  1. 10.002 035 61: first three significant figures are 2, 0, 3, next digit 5 rounds up
  2. 2= 0.00204 (= 2.04 × 10⁻³)

Answer0.00204 or 2.04 × 10⁻³

Part (b) · 2 marks

Estimate (√3.93 × 63.7) ÷ 0.425 after writing each number to 1 significant figure.

  1. 13.93 ≈ 4, 63.7 ≈ 60, 0.425 ≈ 0.4
  2. 2(√4 × 60)/0.4 = (2 × 60)/0.4 = 120/0.4
  3. 3= 300

Answer300

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