How long will it take to make 25 units if the first one took 8 hours and there is a 90 percent learning rate? Refer to the copy of Table I.1 appended to this exam.
A)fewer than or equal to 130 hours
B)greater than 130 hours but fewer than or equal to 140 hours
C)greater than 140 hours but fewer than or equal to 150 hours
D)greater than 150 hours

Question

Quizplus · Accepted Answer

Using the 90% learning rate, we can find the expected time for the 25th unit using the formula: 
Expected time for 25th unit = (time for first unit) * (# of units)^0.5 
Plugging in the values, we get:
Expected time for 25th unit = 8 * (25)^0.5 
Expected time for 25th unit = 40 
Therefore, the total time for making 25 units would be 40 hours multiplied by the efficiency factor of 1.03 (obtained from Table I.1 for 90% learning rate) which gives us a total time of 41.2 hours. 
Since 41.2 hours fall between the range of 140 to 150 hours, the correct answer is C.

How Long Will It Take to Make 25 Units If