The fourth proportional to 0.12,0.21 and 8 is · ABC26GN3034
Subject: General Aptitude · Chapter: Ratio and Proportion
The fourth proportional to $0.12,0.21$ and 8 is
(a)8.9
(b)14
(c)17
(d)56
Answer
Answer (as printed): B
Explanation
Let the fourth proportional to 0.12, 0.21 and 8 be $x$. Then, $0.12: 0.21:: 8: x \Leftrightarrow 0.12 x=0.21 \times 8$ $$\Leftrightarrow x=\frac{0.21 \times 8}{0.12}=\frac{21 \times 8}{12}=14 .$$
Explanation as extracted from the printed page; notation may be imperfect.