1. Problem 8.2: How many 5 ml medicine measures are in 0.5 litres? 2. Formula: Number of measures = Total volume / Volume per measure 3. Convert 0.5 litres to millilitres: $$0.5 \text{ litres} = 0.5 \times 1000 = 500 \text{ ml}$$ 4. Calculate number of measures: $$\frac{500 \text{ ml}}{5 \text{ ml}} = 100$$ 5. Answer: There are 100 medicine measures in the bottle. --- 6. Problem 8.3: Calculate the surface area of a matchbox with dimensions 5.3 cm, 37 mm, and 19 mm. 7. Convert all dimensions to the same unit (cm): - 37 mm = 3.7 cm - 19 mm = 1.9 cm 8. The matchbox is a rectangular prism with length $l=5.3$ cm, width $w=3.7$ cm, height $h=1.9$ cm. 9. Surface area formula for rectangular prism: $$SA = 2(lw + lh + wh)$$ 10. Calculate each area: - $lw = 5.3 \times 3.7 = 19.61$ cm$^2$ - $lh = 5.3 \times 1.9 = 10.07$ cm$^2$ - $wh = 3.7 \times 1.9 = 7.03$ cm$^2$ 11. Sum and multiply by 2: $$SA = 2(19.61 + 10.07 + 7.03) = 2(36.71) = 73.42 \text{ cm}^2$$ 12. Answer: The surface area of the matchbox is 73.42 cm$^2$. --- 13. Problem 8.4: Figure A is a triangle with inner dotted lines; Figure B is a net of a 3D shape made of connected polygons. 14. Explanation: Figure A likely shows a triangle subdivided by lines, possibly for area or angle calculations. 15. Figure B is a net of a 3D solid composed of squares and triangles, which can be folded to form the solid. 16. Without specific measurements or questions, we identify that Figure B represents the net of a polyhedron combining triangular and square faces. 17. This helps understand 3D shapes and their 2D nets. Final answers: - 8.2: 100 medicine measures - 8.3: Surface area = 73.42 cm$^2$ - 8.4: Identification and understanding of shapes and nets.