If A : B : C = 1 : 4 : 7 and B = (2x)% of (A + C), then x is:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 25
A ratio gives each quantity as a multiple of one common number, so A, B and C can be written as \(k\), \(4k\) and \(7k\).
The sum of the first and last parts: \(A+C=k+7k=8k\)
\(B=\displaystyle\frac{2x}{100}\times(A+C)\), so \(4k=\displaystyle\frac{2x}{100}\times8k\)
The \(k\) cancels: \(\displaystyle\frac{2x}{100}=\frac{4k}{8k}=\frac{1}{2}\), so \(2x=50\)
Hence \(x=25\): B is 50% of A + C