Bottom-Up Estimating

Correct Answer: Add up the individual estimates to calculate the total cost.

The bottom-up approach to cost estimation involves adding up the individual cost components or estimates to calculate the total cost. This is why option with the answer text 'Add up the individual estimates to calculate the total cost.' is correct. The rest of the options are incorrect because, for option with answer text 'Pick the highest estimate and use it as a total cost.', this approach could lead to a significant overestimation of costs, while the option with answer text 'Calculate the average of the estimates and multiply by the number of parts.' could lead to an underestimation if costs are not evenly distributed among parts. The last option with the answer text 'Ignore the individual estimates and ask the finance department for a total cost.' risks to overlook the nuances of the project costs, which are understood better by the engineering team.

Correct Answer: Aggregation of all the individual cost estimates for a comprehensive cost.

In bottom-up estimating, the most accurate way to determine the overall project's cost is by aggregating or adding up all the individual cost estimates. This creates a comprehensive and complete cost estimate. This method allows for specificity and granularity, making the estimate more accurate. Other options are less accurate. Using the cost of the most expensive system as the project cost does not take into account the cost of all systems and could significantly overshoot the budget. Asking each team to come up with a new overarching estimate would not give an accurate overarching estimate because individual teams only deal with parts of the project and don't necessarily have the overarching view. Taking a random sample and estimating based on that may result in an estimate that's not representative of the total project cost because it makes the assumption that the cost of the sampled systems is representative of all systems, which may not be true.

Correct Answer: Starting from the individual estimates for the swing set, slide, and monkey bars, consolidate them all to calculate the total cost of the playground.

In a bottom-up estimate process, the estimation starts from determining the cost of individual, smallest work package or activities which in this case are the estimates for the swing set, slide, and monkey bars. These individual estimates are then aggregated to calculate the total cost of the project, which is the construction of the playground, instead of starting with the total cost and dividing it equally, calculating an average, or stretching the small estimates to match the highest. This allows for a more realistic and accurate project estimation based on actual work packages or activities involved. The other three methods may overlook the unique costs associated with different parts of the project.