At Nadia's minimart, 840 rolls of paper towels were packed into cartons. Each carton held either 8 large rolls or 11 small rolls. The number of cartons holding large rolls was 3 times the number of cartons holding small rolls. How many cartons were used altogether?
Need a hint?
Draw one group containing 1 small-roll carton and 3 large-roll cartons. How many rolls does this group hold?
Worked answer
- Show 1 carton of small rolls and 3 cartons of large rolls as one group: 11 + 3 × 8 = 35 rolls.
- There are 840 ÷ 35 = 24 groups, so 24 × 4 = 96 cartons were used.
Answer: 96 cartons
The mistake this question tests
Habit
Stopped at one part in ratio
Dividing 840 by 11 assumes that every carton held 11 rolls. The two carton sizes must first be combined using the given ratio.
How to fix it at home →More PSLE ratio questions
Short answer · 2m
The ratio of boys to girls in a class is 3 : 5
See the answer →Structured · 3mPriya and Marcus had some stickers each
See the answer →MCQ · 2mPoints P, Q, R, S and T lie in that order on a straight path
See the answer →Short answer · 2mOn Arun's town map, 3 cm represents 15 km
See the answer →Structured · 4mA box contains red and blue beads
See the answer →MCQ · 2mIn a park, the ratio of the number of trees in Garden P to the number of trees in Garden Q is 3 : 5
See the answer →Practise PSLE ratio 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.