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Re: a is directly proportional to b. If a = 8 when b = 2, what
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28 Jul 2018, 16:18
Explanation
To answer this question, it is important to understand what is meant by the phrase “directly proportional.”
It means that \(a = kb\), where k is a constant.
In alternative form: = k, where k is a constant.
So, because they both equal the constant, \(\frac{a_{old}}{b_{old}}=\frac{a_{new}}{b_{new}}\). Plugging in values: \(\frac{8}{2}=\frac{a_{new}}{4}\).
Crossmultiply and solve:
\(32 = 2a_{new}\)
\(a_{new} = 16\)