The ratio of the coefficient of $x^{15}$ to the term independent of $x$ in $\left(x^{2}+\frac{2}{x}\right)^{15}$, is
(a) 12 : 32
(b) 1 : 32
(c) 32 : 12
(d) 32 : 1
$\ln \left(x^{2}+\frac{2}{x}\right)^{15}$ we have $T_{r+1}={ }^{15} C_{r}\left(x^{2}\right)^{15-r}\left(\frac{2}{x}\right)^{r}$
i.e. General term is $T_{r+1}={ }^{15} C_{r} x^{30-3 r} 2^{r}$
Hence for the term independent of x,
30 – 3r = 0
i.e. r = 10
hence T11 has coefficient 15C10 210 ...(1)
and term with x15 will have 30 – 3r = 15
i.e. 15 = 3r
i.e. r = 5
∴ coefficient will be 15C5 25 ...(2)
∴ ratio of coefficient of x15 to the term independent of x will be
$\frac{e q^{n}(2)}{e q^{n}(1)}=\frac{2^{5} \times{ }^{15} C_{5}}{2^{10} \times{ }^{15} C_{10}}$
$=\frac{1}{2^{5}} \quad\left(\because{ }^{15} C_{10}={ }^{15} C_{5-10}={ }^{15} C_{5}\right)$
i.e. ratio will be 1 : 32
Hence, the correct answer is option B.