A pair of leather boots is marked $200 before GST. In a sale, the shop gives a discount on the marked price, then adds 9% GST on the discounted price. Ms Quek pays $130.80 in total for the boots.
- Find the price of the boots before GST that Ms Quek paid for.
- Find the amount of GST she paid.
- Find the discount, in dollars, given on the marked price.
- Find the percentage discount given in the sale.
Need a hint?
Work backwards: the $130.80 includes GST, so divide by 1.09 first to find the discounted price before GST. Then compare it with the marked price.
Worked answer
- (a) Total paid is 109% of the discounted price, so 130.80 ÷ 1.09 = 120; the price before GST is $120.
- (b) GST = 130.80 − 120 = $10.80.
- (c) Discount = 200 − 120 = $80.
- (d) Percentage discount = 80 ÷ 200 × 100 = 40%.
The mistake this question tests
Percentage of a new total
Pupils subtract the total paid ($130.80) from $200 to get $69.20 and then work out 34.6%. The discount must be found from the price before GST, not the total including GST.
How to fix it at home →More PSLE percentage questions
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See the answer →Practise PSLE percentage until the mistakes stop.
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