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A. An electronics store makes a profit of $4 000 on each desktop computer sold and $6 000 on each laptop computer. In any month, a maximum of 90 desktops and 70 laptops are supplied to the store. Since it takes 3 hours per desktop and 4 hours per laptop to install software a maximum of 400 hours is set aside each month for software installations. Defining any variables used, formulate a linear programming model that could be used to determine the maximum monthly profit from the sale of the computers. Use an appropriate method to solve this problem.

B. The table below shows the duration of six activities A to F required for a project. It also indicates which activities precede others. Construct an activity network for this project and determine the expected completion time for this project. Activity Duration (hours) Preceded by A 7 – B 9 – C 3 A, B D 4 B E 6 C F 2 D, E

Activity	Duration (hours)	Preceded by
A	7	–
B	9	–
C	3	A, B
D	4	B
E	6	C
F	2	D, E