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anonymous

  • 5 years ago

a cylindrical container of V=450 is to be made of different material for bottom is R60per square metre, for curved side is R200per square metre and the lid is R160per square metre. what is the least cost of the container in rands?

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  1. anonymous
    • 5 years ago
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    v = pi * (radius^3) r^3 = 450 / pi radius = \[\sqrt[3]{450/\pi}\]

  2. anonymous
    • 5 years ago
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    v=450 cubic metre

  3. amistre64
    • 5 years ago
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    surface area = pi r^2(R60) + pi r^2(R160) + 2pi r(R200)

  4. amistre64
    • 5 years ago
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    surface area = pi r^2(R60) + pi r^2(R160) + 2pi r(R200)(h) volume = pi r^2 (height) 450 = pi r^2 * h 450/pi r^2 = h ------------------------------ surface area = pi r^2(60) + pi r^2(160) + 2pi r(200)(450/pi r^2)

  5. amistre64
    • 5 years ago
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    Sa = pi r^2(60+160) + 2.200.450/r Sa = pi r^2(220) + 180000/r Sa = (pi r^3(220) + 180000)/r Sa' = [660 pi r^3 - 220pi r^3 - 180000]/r^2 440 pir^3 - 180000 = 0 when..... r =abt. 2.363

  6. amistre64
    • 5 years ago
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    err... r =abt. 5.07

  7. anonymous
    • 5 years ago
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    yip and cost is R 53 268.91

  8. amistre64
    • 5 years ago
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    the derivative is right; just gotta see if i can find a common answer for r lol

  9. amistre64
    • 5 years ago
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    440 pir^3 = 180000 r^3 = 4500/11 pi r = cbrt(4500/11 pi) perhaps?

  10. amistre64
    • 5 years ago
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    r = abt 5.07...thats good lol

  11. amistre64
    • 5 years ago
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    450/[pi (5.07)^2] = h = abt 5.57

  12. anonymous
    • 5 years ago
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    thanks everyone

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