Girish Shambu and William Reisel are teammates at a discount store; their new job is assembling bicycles for customers. Assembly of a bike has a learning rate of 90%. They forgot to time their effort on the first bike, but spent 4 hours on the second set. They have 6 more bikes to do.
Determine approximately how much time will be (was) required for:
a) the 1st unit.
b) the 8th unit.
c) all 8 unit.