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    I have some measurements below:

    a1 = 96.0

    c1 = 1.25

    a2 = 60.0

    c2 = 0.50

    It is suggested that 'c' is proportional to 'a' cubed. Show whether this is true within a 12% tolerance. I'm not sure how to go about this. I guess you find the constant of proportionality first so:

    1.25/96^3 = 1.4 x 10^-6

    0.50/60^3 = 2.3 x 10^-6

    Can you just add 12% onto the lower number: 1.4 x 10^-6 x 1.15 = 1.61 x 10^-6. Therefore it is not within the tolerance?

    Another way I thought would be to use one of the constants calculated and use it to find the expected value in the other set of values:

    If we take 1.4 x 10^-6 to calculate the expected value of c2:

    c2 = 1.4 x 10^-6 x 60^3 = 0.30

    But we know c2 to be 0.50 so then we can do:

    (50-30)/30 = 67%

    Is that right, that seems really high to me?
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