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 units.