Fourth proportion to 12, 18, and 6 is same as the third proportion to k and 6. What is the value of k ?
Answer & explanation
Correct answer: option 2
Fourth proportion of A, B, C = $\frac{B\; \times\;C}{A}$
Fourth proportion to 12, 18, 6 = \(\frac{18\; \times\; 6}{12}\)
= 9
Third proportional of A and B = \(\frac{B\; \times\;B}{A}\)
Third proportion to k, 6 = \(\frac{6\; \times\; 6}{k}\)
⇒ 9 = 36/k
⇒ k = 4