Answer:
(a) Surface Area = 140 π cm² = 438.823 cm²
(b) Volume = 147 π cm³ = 461.814 cm³
(c) Doubling the radius, keeping height constant results in more volume
Explanation:
Volume of a cylinder with base radius r and height h is given by
V = π r² h
Surface Area A = 2 π r(h + r)
Given r = 7 cm, height = 3cm
(a) Surface Are = 2 x π x 7(7 + 3) = 14 π (10) = 140 π cm² =438.823 cm²
(b) Volume = π x 7² x 3 = 147 π = 461.814 cm³
(c) If we double the radius to 14 cm with height at 3 cm (Option 1), the volume would quadruple to 4 because the new radius is twice the old radius and since volume is proportional to square of radius, new volume will be (2r)² = 4r² where r is the old radius
So new volume = 4 x 461.814 = 1,847.256 cm³
If we triple the height to 9 cm, keeping radius at 7, the volume would only triple since it is directly proportional to height
So new volume = 3 x 461.814 = 1,385.442 cm³
So to get more volume, idea 1, doubling the radius works