# Direct & Joint Proportions

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• October 14th 2011, 05:18 PM
gellie
Direct & Joint Proportions
Please help me answer this problem. Thank you so much :)

If n is directly proportional to the cube of m and that n = 27 when m = 1 1/2, find:
a) the value of n when m = 2
d) the value of m when n = 125
• October 14th 2011, 08:26 PM
mr fantastic
Re: Direct & Joint Proportions
Quote:

Originally Posted by gellie
Please help me answer this problem. Thank you so much :)

If n is directly proportional to the cube of m and that n = 27 when m = 1 1/2, find:
a) the value of n when m = 2
d) the value of m when n = 125

$n \propto m^3 \Rightarrow n = km^3$.

Use n = 27 when m = 1 1/2 to get the value of k. Then use your formula to answer a) and d).

If you need more help, please show all your work and say where you're stuck.