The first, third and fourth terms of a proportion are 8, 16 and 6 res…

Fourth proportion(d) to a, b, c = $\frac{b\; \times\;c}{a}$

Here, the second term(b) = $\frac{a\; \times\;d}{c}$

                                      = $\frac{8\; \times\;6}{16}$

                                      = 3