Math Problem Statement

The cylindrical tin of jam is enclosed at both sides. It has a height of 24 cm and a radius of 15 cm. Determine: (7.1) the volume of the tin, (7.2) the total surface area of the tin, and (7.3) the total surface area if the dimensions are doubled.

Solution

Let's analyze and solve the questions step-by-step from the image.

Given:

  • Height (hh) = 24cm24 \, \text{cm}
  • Radius (rr) = 15cm15 \, \text{cm}

The cylindrical tin is closed on both ends. For a cylinder:

  • Volume (VV) = πr2h\pi r^2 h
  • Surface Area (AA) = 2πr2+2πrh2\pi r^2 + 2\pi r h, which includes both the circular ends and the curved side.

7.1: Volume of the tin

V=πr2hV = \pi r^2 h Substitute r=15cmr = 15 \, \text{cm} and h=24cmh = 24 \, \text{cm}: V=π(15)2(24)=π(225)(24)=5400πcm3V = \pi (15)^2 (24) = \pi (225)(24) = 5400\pi \, \text{cm}^3 Using π3.1416\pi \approx 3.1416: V5400×3.1416=16,964.6cm3V \approx 5400 \times 3.1416 = 16,964.6 \, \text{cm}^3


7.2: Total Surface Area of the tin

A=2πr2+2πrhA = 2\pi r^2 + 2\pi r h Substitute r=15cmr = 15 \, \text{cm} and h=24cmh = 24 \, \text{cm}: A=2π(15)2+2π(15)(24)A = 2\pi (15)^2 + 2\pi (15)(24) A=2π(225)+2π(360)=450π+720π=1170πcm2A = 2\pi (225) + 2\pi (360) = 450\pi + 720\pi = 1170\pi \, \text{cm}^2 Using π3.1416\pi \approx 3.1416: A1170×3.1416=3,674.5cm2A \approx 1170 \times 3.1416 = 3,674.5 \, \text{cm}^2


7.3: Total Surface Area if the dimensions are doubled

If both rr and hh are doubled:

  • New radius = 2r=30cm2r = 30 \, \text{cm}
  • New height = 2h=48cm2h = 48 \, \text{cm}

New surface area: Anew=2π(2r)2+2π(2r)(2h)A_{\text{new}} = 2\pi (2r)^2 + 2\pi (2r)(2h) Anew=2π(30)2+2π(30)(48)A_{\text{new}} = 2\pi (30)^2 + 2\pi (30)(48) Anew=2π(900)+2π(1440)=1800π+2880π=4680πcm2A_{\text{new}} = 2\pi (900) + 2\pi (1440) = 1800\pi + 2880\pi = 4680\pi \, \text{cm}^2 Using π3.1416\pi \approx 3.1416: Anew4680×3.1416=14,702.1cm2A_{\text{new}} \approx 4680 \times 3.1416 = 14,702.1 \, \text{cm}^2


Final Answers:

  1. Volume of the tin: 16,964.6cm3\mathbf{16,964.6 \, \text{cm}^3}
  2. Total Surface Area: 3,674.5cm2\mathbf{3,674.5 \, \text{cm}^2}
  3. Total Surface Area if dimensions are doubled: 14,702.1cm2\mathbf{14,702.1 \, \text{cm}^2}

Would you like further details or help with similar problems? Here are some related questions:

  1. How does doubling dimensions affect the volume of the cylinder?
  2. Can you calculate the ratio of the new surface area to the original surface area?
  3. What happens to the curved surface area if only the height is doubled?
  4. How does the surface area change if only the radius is doubled?
  5. How do real-life factors (e.g., material thickness) affect these calculations?

Tip: Always separate the contributions of the curved surface area and the two circular bases for clarity when solving surface area problems.

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Math Problem Analysis

Mathematical Concepts

Geometry
Cylindrical Volume
Surface Area Calculations

Formulas

Volume of a cylinder: V = πr²h
Surface area of a cylinder: A = 2πr² + 2πrh

Theorems

Properties of cylinders in Euclidean geometry

Suitable Grade Level

Grade 10