Each robot kit cost $3.25 more than each puzzle. Nadia bought two puzzles for every robot kit. She paid $60.00 altogether. She paid $6.00 more for the robot kits than for the puzzles.
- Find the amount Nadia paid for robot kits and the amount she paid for puzzles.
- Find the total cost of 3 robot kits and 2 puzzles.
Need a hint?
Use the total bill and the extra amount spent on robot kits to find the two spending totals. Then use the two-puzzles-per-kit ratio to find the unit prices.
Worked answer
- (a) Robot kits: ($60.00 + $6.00) ÷ 2 = $33.00.
- Puzzles: $60.00 − $33.00 = $27.00.
- There are 2 puzzles for every robot kit. If each puzzle cost as much as a robot kit, the puzzles would cost 2 × $33.00 = $66.00.
- They cost $27.00, which is $66.00 − $27.00 = $39.00 less.
- Each puzzle costs $3.25 less than a robot kit, so there were $39.00 ÷ $3.25 = 12 puzzles and 12 ÷ 2 = 6 robot kits.
- One robot kit costs $33.00 ÷ 6 = $5.50. One puzzle costs $5.50 − $3.25 = $2.25.
- (b) 3 robot kits and 2 puzzles cost 3 × $5.50 + 2 × $2.25 = $16.50 + $4.50 = $21.00.
The mistake this question tests
Average and total
A common mistake is to divide $60.00 equally, giving $30.00 for each kind of item. This ignores the $6.00 difference in the amounts Nadia spent.
How to fix it at home →More PSLE algebra questions
Nora has s stickers
See the answer →Short answer · 2mAmir and Sofia are making a triangular sign for a community garden
See the answer →MCQ · 1mIn a video game, Ravi’s final score is represented by 16 + 7k + 9 – 2k + 11 – 6 points
See the answer →Structured · 3mA bag of marbles was shared among three children
See the answer →MCQ · 2mAt a bookshop, there were equal numbers of novels, poetry books and picture books at first
See the answer →Structured · 4mMr Tan received p cartons of eggs
See the answer →Practise PSLE algebra until the mistakes stop.
Three PSLE questions, free, no sign-up. You’ll see exactly where the marks went. Then 7 days of everything for S$4.99.