Question 1: Calculate 15% of 240 kilograms, which represents the mass of fallen leaves in a park.

Answer: 36

Question 2: A conservation project reduces water usage by 25%. If the initial water usage was 80,000 liters per week, how much water is saved weekly?

Answer: 20000

Question 3: A forest reserve has 150 species of trees. If 12% of these are endangered, how many endangered species are there?

Answer: 18

Question 4: Calculate 8.5% of 600 liters to find the amount of water that evaporates daily in a wetland area.

Answer: 51

Question 5: A park has 120 trees, and 20% of them are oak trees. How many oak trees are there?

Answer: 24

Question 6: A scientist observes that 18% of a pond's algae coverage has increased over a month. If the algae covered 50 square meters initially, what is the new coverage?

Answer: 59

Question 7: A wildlife sanctuary increases its protected habitat area by 10% annually. If the current area is 250 hectares, what will be its area after one year?

Answer: 275

Question 8: Construct a diagram on the grid to represent a triangle with a base of 6cm and height of 4cm, then calculate its area. (Note: Use the grid for drawing.)

Answer: 12

Question 9: Plot the graph of y=2x on the grid. Label the points for x=0, 2, 4, and 6.

Answer: Points: (0,0), (2,4), (4,8), (6,12)

Question 10: A scientist estimates that 60% of a forest area has been affected by pests. If the total forest area is 500 hectares, how much area is unaffected?

Answer: 200

Question 11: Error analysis: A student calculates 20% of 150 as 30, but then states the answer is 20. Identify and correct the mistake.

Answer: Correct answer: 30. Mistake: Incorrectly wrote the answer as 20 instead of 30.