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# Help!

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Suppose j and k are inversely proportional. If j = 16 when k = 21, find the value of j  when k = 14 .

Logic  Aug 22, 2018
#1
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Inversely proportional means basically that the product of the numerator and denominator will always be the same. So if the fraction is $$\frac{16}{21} = \frac{j}{k}$$, the product of $$16\times21 = 336$$. We are trying to find $$j$$ if $$k = 14$$. We have $$\frac{16}{21} = \frac{j}{14}$$. You can solve this by doing $$336$$ divided by $$14$$, which gives you $$24$$$$j = 24$$.

- Daisy

dierdurst  Aug 22, 2018
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Thanks Daisy!!!!....here's another way

j  = C / k      where C is the proportionality constant

And we know that

16 = C / 21      multiply both sides by 21

336  = C

So  when  k = 14  we have that

j = 336 / 14  =   24

CPhill  Aug 22, 2018
#3
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That makes sense, too! Thanks Chris!

- Daisy

dierdurst  Aug 22, 2018