Final answer:
The learning rate is calculated by comparing the time it took to produce the second and fourth units. After applying the formula for learning rates, the answer is found to be 90%, making option (c) the correct choice.
Step-by-step explanation:
To determine the learning rate for a product that took 200 hours to produce the second unit and 180 hours to produce the fourth unit, we will use the formula for calculating learning rates, which is essentially the rate at which production time decreases as more units are produced.
The learning rate is determined by the formula:
Learning Rate = (Time for nth unit / Time for 1st unit) ^ (1/(n-1))
In this case, we can assume the 'n' is doubled from the 2nd to the 4th unit, so we use the formula for two doubling periods (2nd to 4th unit).
Learning Rate = (180 / 200) ^ (1/(4/2-1))
Learning Rate = (0.9) ^ (1/1) = 0.9 or 90%
Hence, the learning rate is 90%, which corresponds to option (c).