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The surface area of a solid metallic sph...

The surface area of a solid metallic sphere is `2464 cm^(2).` It is melted and recast into solid right circular cones of radius 3.5 cm and height 7 cm. Calculate :
the number of cones recast. (Take `pi = (22)/(7))`

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To solve the problem of finding the number of cones that can be recast from a solid metallic sphere with a given surface area, we will follow these steps: ### Step 1: Calculate the radius of the sphere The surface area \( S \) of a sphere is given by the formula: \[ S = 4 \pi r^2 \] Given that the surface area \( S = 2464 \, \text{cm}^2 \) and \( \pi = \frac{22}{7} \), we can set up the equation: \[ 2464 = 4 \times \frac{22}{7} \times r^2 \] ### Step 2: Rearranging the equation to find \( r^2 \) First, we will multiply both sides by \( \frac{7}{22} \): \[ r^2 = \frac{2464 \times 7}{4 \times 22} \] ### Step 3: Simplifying the equation Calculating the right-hand side: \[ r^2 = \frac{2464 \times 7}{88} \] Now, simplify \( 2464 \div 88 \): \[ 2464 \div 88 = 28 \] Thus, \[ r^2 = 28 \times 7 = 196 \] ### Step 4: Finding the radius \( r \) Taking the square root of both sides: \[ r = \sqrt{196} = 14 \, \text{cm} \] ### Step 5: Calculate the volume of the sphere The volume \( V \) of a sphere is given by the formula: \[ V = \frac{4}{3} \pi r^3 \] Substituting \( r = 14 \, \text{cm} \): \[ V = \frac{4}{3} \times \frac{22}{7} \times (14)^3 \] ### Step 6: Calculating \( 14^3 \) Calculating \( 14^3 \): \[ 14^3 = 2744 \] Now substituting back into the volume formula: \[ V = \frac{4}{3} \times \frac{22}{7} \times 2744 \] ### Step 7: Simplifying the volume calculation Calculating \( \frac{4 \times 22 \times 2744}{3 \times 7} \): \[ V = \frac{241792}{21} \] ### Step 8: Calculate the volume of one cone The volume \( V_c \) of a cone is given by the formula: \[ V_c = \frac{1}{3} \pi r_c^2 h_c \] Where \( r_c = 3.5 \, \text{cm} \) and \( h_c = 7 \, \text{cm} \): \[ V_c = \frac{1}{3} \times \frac{22}{7} \times (3.5)^2 \times 7 \] ### Step 9: Calculate \( (3.5)^2 \) Calculating \( (3.5)^2 = 12.25 \): \[ V_c = \frac{1}{3} \times \frac{22}{7} \times 12.25 \times 7 \] The \( 7 \) cancels out: \[ V_c = \frac{1}{3} \times 22 \times 12.25 \] ### Step 10: Final calculation for volume of one cone Calculating \( 22 \times 12.25 = 270.5 \): \[ V_c = \frac{270.5}{3} = 90.1667 \, \text{cm}^3 \] ### Step 11: Calculate the number of cones The number of cones \( n \) that can be made is given by: \[ n = \frac{V}{V_c} \] Substituting the volumes: \[ n = \frac{241792/21}{90.1667} \] ### Step 12: Final calculation for number of cones Calculating \( n \): \[ n = \frac{241792}{21 \times 90.1667} \approx 128 \] Thus, the number of cones that can be recast from the melted sphere is **128**.
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