Doris and Dennis Datcher, experts at DIY, want to build a summerhouse in their garden. They will start by drawing up a proper plan, which they can complete in 2 days. Once they have a plan they can prepare the site, which will take 6 days, order the timber, which will be delivered in 10 days from placing the order, and purchase the ironmongery, which will take 2 days. Once they have the timber and ironmongery they can construct the floor panels, which will take 4 days, make the frames for the walls, which will take 2 days, and construct the door, which will take 1 day. When they have made the wall frames they can board them up, which will take 2 days. When they have prepared the site and constructed the floor panels they can lay the floor, which will take 1 day. As soon as the floor is laid and the wall frames boarded they can erect the walls, which will take 1 day. Once the walls are erected the roof joists can be fixed, which will take 2 days. Having fixed the roof joists the roof can be boarded and weatherproofed, which will take 4 days. Once the door has been constructed and the walls erected they can hang the door, which will take 1 day.
(a) List the activities involved in building the summerhouse and identify the predecessor activities for each of them as well as their durations.
(b) Draw a network diagram for the building of the summerhouse and from it identify the critical path and the minimum duration of the project.