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4024/12 May/Jun 2022, Question 4: Directed Numbers

Cambridge O Level Mathematics 4024 · Paper 12 (Non-calculator) · Non-calculator · 2 marks

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The question, in short

Compare inside and outside temperatures, finding their difference, and use rounding to the nearest degree to find an upper bound for a −6 °C reading.

Summarised in our own words. Use the official paper for the exact wording and any diagrams.

Part (a) · 1 mark

Find the difference between an inside temperature of 18 °C and an outside temperature of −3 °C.

  1. 118 − (−3) = 18 + 3
  2. 2= 21 °C

Answer21

Part (b) · 1 mark

Given a thermometer reading of −6 °C correct to the nearest degree, find the upper bound of the actual temperature.

  1. 1Nearest degree, so the true value is within 0.5 of −6
  2. 2Upper bound = −6 + 0.5 = −5.5 °C

Answer−5.5

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Also searched as: 4024/12/M/J/22 · 4024_s22_qp_12 · 4024 s22 12 · question 4.
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