Question 15
The project network diagram shows a student’s morning activities.
Which statement is correct?
Not quite. Every activity in a project network gets done. The student still charges the phone and listens to music. The critical path only decides the shortest time the whole morning can take. In 2025, 5.6% of Queensland students chose (A).
Not quite. Charge phone runs alongside get dressed and pack bag, and listen to music runs alongside eat breakfast and brush teeth. Two paths between the same pair of nodes mean those activities can happen at the same time. In 2025, 5.1% of Queensland students chose (B).
Not quite. Wash face, get dressed, pack bag and charge phone all have to finish before listening to music can start. That’s 4 of the 8 activities, exactly half, and half isn’t less than half. In 2025, 6.5% of Queensland students chose (C).
That’s it. Step through the hints below to see why. In 2025, 82.0% of Queensland students chose (D).
Each arrow is one activity. Count them: wash face, get dressed, pack bag, charge phone, eat breakfast, brush teeth, listen to music and travel to school. That’s 8.
Every one of the 8 gets done. A critical path tells you the shortest time the project can take. It doesn’t cancel the other activities, so (A) is false.
Look for two routes between the same pair of nodes. Get dressed then pack bag runs above charge phone, and eat breakfast then brush teeth runs above listen to music.
Activities on parallel routes can happen at the same time, like charging the phone while getting dressed. So (B) is false.
Count for (C). Listen to music starts at the middle node, so wash face, get dressed, pack bag and charge phone must all finish first. That’s 4 of 8, exactly half, so (C) is false.
Count for (D). After pack bag and before travel to school come eat breakfast, brush teeth and listen to music. That’s 3, so (D) is true. Pick pack bag in the diagram to see it.
Pack bag ends at the middle node. Travel to school starts at the node before Finish. The activities between those two nodes are eat breakfast, brush teeth and listen to music.
$$\text{eat breakfast}+\text{brush teeth}+\text{listen to music}=3\text{ activities}$$
The others fail: every activity is completed (A), charge phone and listen to music run in parallel with other activities (B), and 4 of 8 before listen to music is exactly half (C).
Only mark this done when you could do it without help. Reading the solution does not count.
Question wording is from the 2025 QCAA General Mathematics external assessment, © State of Queensland (QCAA) 2025, licensed under CC BY 4.0, and has been adapted. Tangent Tuition is not affiliated with the QCAA.
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