Common Parameters of Machining Operation

Q. The speed range ratio of a machine tool is (where the symbols used have their usual meanings)

1. $\frac{D_{max}\times V_{min}}{D_{min}\times V_{max}}$
2. $\frac{D_{max}\times V_{max}}{D_{min}\times V_{min}}$
3. $\frac{D_{min}\times V_{max}}{D_{max}\times V_{min}}$
4. none