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St Nicholas 2025 P6 Maths Prelim — Paper 2 Q9a Solution

Paper 2 · Q9a · 2 marks · Percentage

Question

An electrical company charges \$0.25 per unit for the first 180 units and \$0.35 per unit for any usage above 180 units (before GST). (a) In January, the Wang family used 260 units of electricity. How much did the Wang family pay for their usage after including a 9% GST?
Answer: $79.57

Worked solution

  1. Charge $= 180 \times \$0.25 + (260 - 180) \times \$0.35 = \$45 + \$28 = \$73$. With 9% GST: $\$73 \times 1.09 = \$79.57$.

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