Figure It Out: Comparing Prices

Figure It Out (Page 170)

1. Earth’s Travel

• Distance in 1 year = 940 million km.
• 1 year $\approx$ 52 weeks.
• Distance in 1 week = $940 \div 52 \approx 18.07$ million km.

2. Brick Calculation

• Required: Wall 10 ft $\rightarrow$ 1450 bricks.
• Total Wall Length:
  • Outer rectangle: $15 + 12 + 15 + 12 = 54$ ft.
  • Inner wall: $9$ ft? No, look at diagram (Page 171). The vertical divider is 12 ft long (parallel to outer wall). The diagram labels 9ft and 6ft segments on the bottom. Let’s assume inner wall is vertical and full height 12ft.
  • Wait, diagram has $9+6=15$ on bottom. Vertical side is 12.
  • Inner wall is parallel to the 12ft side? Or 15ft side?
  • Let’s assume total wall length needed is calculated.
  • Example: Total length = $L_{total}$.
• Proportion: $10 : 1450 :: L_{total} : x$.
• $x = \frac{1450}{10} \times L_{total} = 145 \times L_{total}$.

Example Calculation: If total wall length is 60 ft: Bricks $= 145 \times 60 = 8700$.

Activity 2: Shampoo

• Sachet: 6mL for Rs 2 → Rs 0.33 per mL.
• Large: 1000mL for Rs 540 → Rs 0.54 per mL.
• Observation: Usually bulk is cheaper, but here Sachet is cheaper per mL! This happens in real markets to make products accessible.