In a single pass drilling operation, a through hole of $15$ mm diameter is to be drilled in a steel plate of $50$ mm thickness. Drill spindle speed is $500$ rpm, feed is $0.2$ mm/rev and drill point angle is $118^{\circ}$. Assuming $2$ mm clearance at approach and exit, the total drill time (in seconds) is
- $35.1$
- $32.4$
- $31.2$
- $30.1$