Evaluating Environmental Solutions — Practice · Grade 9 Science

Chapter: Resources & Human Decisions

What this practice covers

By the end of Evaluating Environmental Solutions you should be able to:

8 questions, numeric, multiple choice and written answer, each with a worked explanation.

Vocabulary used: criterion, constraint, life-cycle perspective.

Problem 1

Energy demand falls from 200 to 160 units. Find percent reduction.
Answer and explanation

20 %

40 ÷ 200 × 100 = 20.

Problem 2

Which is a constraint?
  1. Reduce runoff as much as possible
  2. Stay within a $5,000 budget
  3. Measure water use
  4. Compare two designs
Answer and explanation

Stay within a $5,000 budget

The budget limits feasible solutions.

Problem 3

Why should a design be monitored after implementation?
Answer and explanation

Actual outcomes and maintenance can differ from predictions; evidence can guide revision.

Problem 4

Design A reduces modeled runoff from 100 to 70 mL; B reduces it to 55 mL. Compare percentage reductions and name missing evidence. Explain the reasoning in your own words.
Answer and explanation

A gives 30% and B 45% in this model; that alone does not establish the best real design.

A reduction is (100−70)/100×100=30%.

B gives 45%; costs, maintenance, habitat and real-scale behavior are still unknown.

Response criteria

  • Use the stated conditions.
  • Show the evidence or calculation.
  • Explain the conclusion and any stated limitation.

Problem 5

A system saves 3 units/day for 200 days. Estimate annual savings for those operating days. Show the reasoning, not just the conclusion.
Hints

Equivalent outcomes and boundaries make comparisons meaningful.

Answer and explanation

3×200=600 units, assuming the daily saving holds.

Problem 6

What makes a design recommendation scientifically revisable?
Hints

State what the supplied observations or conditions establish, and separate that from any assumption.

Answer and explanation

Measurable success criteria, monitoring and a plan to update choices when observed outcomes differ.

Problem 7

A local improvement can move costs or impacts to another stageA local improvement can move costs or impacts to another stageOne supplied life-cycle metric (units)Manufacture impact35Installed local impact15Maintenance impact20End-of-life impact10Reduced local impact can coexist with other impacts elsewhere.
Original one-metric life-cycle stage example, not an actual product assessment or a hidden multi-criterion score. Values can be added only within that supplied metric/boundary; they do not establish ecological tradeoffs without the other relevant indicators.
Interpret the supplied visual model. Why should a design report include maintenance and later water release rather than only initial runoff capture?
Answer and explanation

Performance and impacts can change over time, and stored water or material effects can shift elsewhere. A boundary ending at capture omits consequential stages of the service.

The four bars share one illustrative impact metric; a complete decision would also compare runoff, cost, accessibility and maintenance separately.

Performance and impacts can change over time, and stored water or material effects can shift elsewhere. A boundary ending at capture omits consequential stages of the service.

Response criteria

  • Read the labeled quantities, reference frame or objects correctly.
  • Explain the relation between the visual evidence and the mechanism.
  • Keep the drawing’s stated assumptions and limits in the conclusion.

Problem 8

A matched storm baseline gives 120 m³ runoff. Design A gives 72 m³ at cost 85; B gives 54 m³ at cost 110. Budget limit is 100. Calculate both reductions, identify feasibility and state a further test before recommending A.
Answer and explanation

A reduces runoff by 40% and meets the cost constraint. B reduces it by 55% but exceeds the budget. Test repeated relevant storm/soil conditions, maintenance and effects elsewhere, checking all success criteria before recommending A.

A: (120−72)/120 = 0.40 = 40%.

B: (120−54)/120 = 0.55 = 55%, but cost 110 exceeds 100.

Evaluate repeated performance, life-cycle effects and maintenance within the defined service.

Response criteria

  • Use the stated measurements or conditions, with correct units.
  • Connect the result to the physical mechanism or evidence relationship.
  • Identify the assumption, model limit or further evidence requested.

Browse all courses