Correct Answer - Option 1 :
\(\frac{{\mathop N\nolimits_1 }}{{\mathop N\nolimits_n }}\)
Concept:
Speed ratio (or velocity ratio) of the gear train is the ratio of the speed of the driver to the speed of the driven or follower.
\(Speed\;ratio = \frac{{{\omega _{driver}}}}{{{\omega _{driven}}}} = \frac{{{\omega _1}}}{{{\omega _n}}} = \frac{{{N_1}}}{{{N_n}}} = \frac{{{T_n}}}{{{T_1}}} = \frac{1}{{Train\;Value}}\)
\(Train\;ratio = \frac{{{\omega _{drivev}}}}{{{\omega _{driver}}}} \)