The fourth proportional to 5, 8, 15 is · ABC26GN3033

Subject: General Aptitude · Chapter: Ratio and Proportion

The fourth proportional to 5, 8, 15 is

(a)18

(b)20

(c)21

(d)24

Answer

Answer (as printed): D

Explanation

Let the fourth proportional to 5, 8, 15 be $x$. Then, $5: 8:: 15: x \Leftrightarrow 5 x=8 \times 15 \Leftrightarrow x=\frac{8 \times 15}{5}=24$.

Explanation as extracted from the printed page; notation may be imperfect.

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