Work through the levels in order. Type your answer and press Check — open the worked solution if you get stuck. Answers like -6, 3/4 or 0.25 are typed exactly as shown. A ⭐ Bonus Challenge at the end is extra credit — skip it if the rest was hard work.
15 questions · official format, shuffled order
1 $2400 is invested at simple interest and earns $504 in 6 years. What is the annual interest rate?
Show worked solution
P × N = 2400 × 6 = 14 400, and 504 ÷ 14 400 = 0.035 = 3.5%. (21% is 504 ÷ 2400 — the interest for all six years treated as one.)
2 Mia earns $26 an hour. This week she worked 38 normal hours, 4 hours on Saturday at time-and-a-half and 2 hours on Sunday at double time. What is her pay?
Show worked solution
988 + 156 + 104 = $1248. ($1144 pays all 44 hours at the normal rate.)
3 After a 15% increase, the rent on a flat is $460 a week. What was the rent before the increase?
Show worked solution
460 ÷ 1.15 = $400. ($391 takes 15% off $460, which uses the wrong amount as the 100%.)
4 A price rises by 20% and then the new price falls by 20%. Compared with the original, the final price is
Show worked solution
1.2 × 0.8 = 0.96, so the final price is 4% lower. The 20% fall is taken from a bigger amount than the 20% rise.
5 A laptop costs $1320 including 10% GST. How much of that price is GST?
Show worked solution
1320 ÷ 11 = $120. ($132 is 10% of $1320 — the GST-inclusive price used as if it were the pre-GST price.)
6 Which size of juice is the best buy?
Show worked solution
Per litre: $2.50, $2.20, $2.10, $2.20. The cheapest per litre is 2 L.
7 A salesperson earns a retainer of $500 a week plus 4% commission on everything they sell. One week they earned $1140. What were their sales?
Show worked solution
1140 − 500 = 640, and 640 ÷ 0.04 = $16 000. ($28 500 divides the whole pay by 4%, forgetting the retainer.)
8 A club grew from 175 members to 210 members. What was the percentage increase?
Show worked solution
35 ÷ 175 = 0.2 = 20%. (16.7% divides by 210, the new amount.)
9 How many years does it take $5000 invested at 6% p.a. simple interest to grow to a total of $6500?
Show worked solution
One year earns $300, and 1500 ÷ 300 = 5 years.
10 Shop P sells a pair of shoes for $84 after a 30% discount. Shop Q sells the same shoes for $117 after a 10% discount. By how much did the two shops’ original prices differ?
Show worked solution
P: 84 ÷ 0.7 = $120. Q: 117 ÷ 0.9 = $130. Difference $10. ($33 compares the sale prices, which answers a different question.)
11 Sam invests $2000 at 5% p.a. simple interest.1 After 3 years the interest is $300.
2 After 6 months the interest is $60.
3 After 10 years the investment is worth $3000.
Which statements are correct?
2 After 6 months the interest is $60.
3 After 10 years the investment is worth $3000.
Which statements are correct?
Show worked solution
3 × $100 = $300 (1 ✓). Half a year earns $50, not $60 (2 ✗). 10 years earns $1000, so $3000 in total (3 ✓). 1 and 3.
12 Leo is paid $24 an hour, and time-and-a-half for overtime. One week he worked 38 normal hours and earned $1128. How many hours of overtime did he work?
Show worked solution
38 × 24 = 912, and 1128 − 912 = 216. 216 ÷ 36 = 6 hours.
13 Three stores sell the same jacket. Which store is cheapest after its discount?
Show worked solution
A $56, B $56, C $54. The cheapest is Store C, even though it has the highest marked price.
14 A share price falls by 50%, then rises by 50%. By what percentage must it now rise to get back to its original value?
Show worked solution
100 → 50 → 75. It needs 25 more, and 25 ÷ 75 = 33⅓%.
15 A meal costs $66 including 10% GST.
1 The GST is $6.
2 The price before GST is $60.
3 The GST is 10% of $66.
Which statements are correct?
1 The GST is $6.
2 The price before GST is $60.
3 The GST is 10% of $66.
Which statements are correct?
Show worked solution
66 ÷ 1.1 = $60 (2 ✓), so the GST is $6 (1 ✓). That is 10% of $60, not of $66 — 10% of $66 is $6.60 (3 ✗). 1 and 2.