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4024/22 Oct/Nov 2023, Question 1: Time Calculations

Cambridge O Level Mathematics 4024 · Paper 22 (Calculator) · Calculator · 11 marks

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The question, in short

Calculate Idris's repair charges, completion time, compound interest on $6200 at 1.7% for 4 years, and dollar cost of €760 equipment with 2.5% tax at $1 = €0.84.

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Part (ai) · 2 marks

Find the total charge for a repair lasting 2 hours using $56 first hour plus $12.25 per extra 15 minutes.

  1. 12 hours = first hour + 4 lots of 15 minutes
  2. 256 + 4 × 12.25 = $105.00

Answer105.00

Part (aii) · 3 marks

Given a $166.25 charge starting at 2.30 pm, find the completion time.

  1. 1(166.25 − 56) ÷ 12.25 = 9 lots of 15 minutes
  2. 29 × 15 = 135 minutes = 2 h 15 min
  3. 3Total time = 3 h 15 min
  4. 42.30 pm + 3 h 15 min = 5.45 pm

Answer5.45 pm or 17 45

Part (b) · 3 marks

Calculate total interest earned on $6200 at 1.7% compound interest per year over 4 years.

  1. 1Amount = 6200 × (1 + 1.7/100)⁴ = 6632.47…
  2. 2Interest = 6632.47… − 6200 = $432.47

Answer432.47

Part (c) · 3 marks

Find dollars paid for €760 equipment after adding 2.5% tax, using $1 = €0.84.

  1. 1Cost with tax = 760 × 1.025 = €779
  2. 2In dollars: 779 ÷ 0.84 = 927.38…
  3. 3= $927.38

Answer927.38

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