Final answer:
The estimated variance in the time for activity C is approximately 3.6297 days².
Step-by-step explanation:
To estimate the variance in the time for activity C, we can use the optimistic, most likely, and pessimistic time estimates along with the formula for estimating variance. The formula for variance is (P - O)/6. Let's plug in the values: optimistic time (O) = 0 days, most likely time (M) = 14.512 days, and pessimistic time (P) = 21.778 days.
The variance = (P - O)/6 = (21.778 - 0)/6 = 3.6297 days².
Therefore, the estimated variance in the time for activity C is approximately 3.6297 days².