A cycling helmet is priced at $340 before GST at a sports shop. The shop gives a discount of 15% on this price. GST of 9% is then charged on the discounted price. How much does Mr Koh pay for the helmet?
- $289.00
- $319.60
- $315.01
- $309.40
Need a hint?
Find the price after the discount first, then find 9% of that new price, not of $340.
Worked answer
- Discounted price: 85% of $340 = $340 × 0.85 = $289.00
- GST on the discounted price: 9% of $289 = $26.01
- Total paid: $289.00 + $26.01 = $315.01
Answer: $315.01
The mistake this question tests
Habit
Percentage of a new total
Pupils often add 9% of the original price to the discounted price, or treat the 9% GST as if it reduces the price.
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