Reading & writing · Grades 6–8
A lower meter reading
Read once, answer together, and check your reasoning.
A lower meter reading
A school uses 900 units of water in one week and 720 the next after a conservation campaign. A notice credits the campaign with the entire reduction. The second week, however, has one fewer school day because of a scheduled closure. The environmental group asks for daily usage figures and attendance before estimating the campaign’s effect.
Try it yourself
What is the raw decrease in weekly usage?
What is the raw percentage decrease?
What alternative explanation must be considered?
Why ask for daily usage and attendance?
Check your understanding
Answers and marking notes
- 180
900 − 720 = 180
- 20
180/900 × 100 = 20
- The second week had fewer school days, which could reduce total use independently of the campaign.
The second week had fewer school days, which could reduce total use independently of the campaign.
- These help compare use over similar operating periods and numbers of users.
These help compare use over similar operating periods and numbers of users.
Learning preview · teacher review required. Grade bands are approximate, not official curriculum alignment.