Question
Find the fourth proportion to the following:
$3,5$ and $15$
$3,5$ and $15$
✓
Answer
Let $x$ be the fourth proportion to $3,5$ and $15$
$3: 5:: 15: x $
$\Rightarrow 3 \times x=5 \times 15$
$\Rightarrow x=\frac{5 \times 15}{3}$
$\Rightarrow x=25$
The fourth proportion is $25 .$
$3: 5:: 15: x $
$\Rightarrow 3 \times x=5 \times 15$
$\Rightarrow x=\frac{5 \times 15}{3}$
$\Rightarrow x=25$
The fourth proportion is $25 .$
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