Question

Please answer the questions​

Answer 1

Answer:

5) 9.9 cm³   6)2310 cm³

Step-by-step explanation:

5)

Height of pencil (h) = 21 cm

Radius of wood (R) = 0.4 cm

Radius of lead (r) = 0.1 cm

Volume of wood = πR²h - πr²h

                            = πh( R² - r² )

                            = $\frac{22}{7}$ × 21 × ( (0.4)² - (0.1)²)

                            = 22 × 3 × (0.16 - 0.01)

                            = 66 × 0.15

                            = 9.9 cm³

6)

Height of cylinder = 15 cm

Circumference of base = 44 cm

⇒2πr = 44

⇒ 2×22/7×r = 44

⇒ 44/7×r = 44

⇒ r/7 = 1

⇒ r = 7 cm

Volume = πr²h

             = $\frac{22}{7}$ × 7 × 7 × 15

             = 22 × 7 ×15

             = 2310 cm³