A factory emitted 1200 tonnes of CO₂ in 2018. After installing a scrubber, emissions reduced by 15% each year. What will be the total emissions in 2021? Round to the nearest tonne.
Answer
737 tonnes
The correct answer is 737 tonnes — Round 736.95 to the nearest whole number, giving 737 tonnes.
Step-by-step solution
- Calculate the emissions for each subsequent year by multiplying the previous year's amount by (1 - 0.15) = 0.85.
- 2019 emissions = 1200 × 0.85 = 1020 tonnes.
- 2020 emissions = 1020 × 0.85 = 867 tonnes.
- 2021 emissions = 867 × 0.85 = 736.95 tonnes.
- Round 736.95 to the nearest whole number, giving 737 tonnes.
Common mistake: Adding 15% each year instead of multiplying by 0.85
Concept tested: Quantitative reduction of pollutants
Published · How this solution was prepared and checked
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