Question

2. The drilling machine is to have six speeds ranging from N1 revolutions/minute (Assume
N1 value as any one of the following: 40 rpm, 50 rpm, 60 rpm 70 rpm, 80 rpm, 90 rpm
or 100 rpm) to 750 revolutions/min. If the speeds form a geometric progression,
determine their values, each correct to the nearest whole number in designing the gear
box for the drilling machine.

Answer 1