Siti packs 4 crates of mangoes in 10 days. Kumar packs 4 crates of mangoes in 5 days. How many days will it take both of them to pack 24 crates when they work together?
Need a hint?
Find how many crates each person packs in one day first, then add the two daily amounts together.
Worked answer
- Siti's rate: 4 crates in 10 days, so 2/5 crate per day.
- Kumar's rate: 4 crates in 5 days, so 4/5 crate per day.
- Together they pack 2/5 + 4/5 = 6/5 crates per day.
- Days needed: 24 ÷ 6/5 = 20 days.
Answer: 20 days
The mistake this question tests
Habit
Calculation slip
Adding the number of days (10 + 5 = 15) is wrong, because the days do not add when two people work at the same time; their daily amounts add instead.
How to fix it at home →More PSLE ratio questions
Structured · 3m
At Mdm Salma's fruit stall, some oranges had been sold by noon
See the answer →Structured · 4mFarid and Lena were paid a total of $2580 for planting trees in a park
See the answer →Structured · 3mA pottery studio had clay bowls and clay vases in the ratio 4 : 7 at first
See the answer →MCQ · 2mA stationery stall had pens and pencils in the ratio 4 : 5 at first
See the answer →MCQ · 2mA bird park had parrots and budgies in the ratio 3 : 8
See the answer →MCQ · 1mWrite the ratio 12 : 18 in its simplest form
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.