The following are the data for the two crossed helical gears used for speed reduction:
Gear I: Pitch circle diameter in the plane of rotation $80$ mm and helix angle $30^{\circ}$
Gear II: Pitch circle diameter in the plane of rotation $120$ mm and helix angle $22.5^{\circ}$
If the input speed is $1440$ rpm, the output speed in rpm is
- $1200$
- $900$
- $875$
- $720$