At 8.00 a.m., a filling machine at Mrs Lim's drink stall began filling empty bottles. It fills 240 bottles per hour. After every 2 hours of filling, it stops for 15 minutes to clean the nozzle. Mrs Lim needs 1 080 bottles filled.
- How much time does the machine spend actually filling the bottles?
- At what time will all 1 080 bottles be filled?
Need a hint?
First find the time spent actually filling. Then count only the breaks that occur before all the bottles are filled.
Worked answer
- 1 080 ÷ 240 = 4 hours 30 minutes of actual filling.
- There are 2 cleaning breaks, after 2 hours and after 4 hours of filling.
- 2 × 15 = 30 minutes of break time.
- 4 hours 30 minutes + 30 minutes = 5 hours.
- 8.00 a.m. + 5 hours = 1.00 p.m.
The mistake this question tests
Minutes and hours in rate
Some pupils may ignore the two cleaning breaks and answer 12.30 p.m. Others may count a third break at 6 hours of filling, even though the filling is already complete.
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