SOLUTION: If m varies directly as n and varies inversely as p, and m=9 when n=3 and p=7, find m when n=5 and p=18.

Question 865382: If m varies directly as n and varies inversely as p, and m=9 when n=3 and p=7, find m when n=5 and p=18.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!

"m varies directly as n and varies inversely as p" means that for some fixed number k (k is a constant).

We are told that "m varies directly as n and varies inversely as p" which means . We're also told that "m=9 when n=3 and p=7". Plug these values into the equation and solve for k.

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Since , we go from to (replace k with 21, since k = 21)

Now we plug in n = 5 and p = 18 into that last equation to find m

<--- This is the answer as a fraction

<--- This is the answer as a decimal (use a calculator. This result will be approximate)
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