Task Planning & Logistics · Guided Practice
Precedence Tables
10 questions with answers and video solutions. Try each one before revealing the answer.
A takes days, then B takes days, then C takes days.
Calculate the minimum time to complete all three tasks.
Answer
A takes hours and B takes hours.
Task C takes hours and can only start once both A and B are finished.
Calculate the minimum time to complete all three tasks.
Answer
B takes days and C takes days.
Task D takes days and starts once both B and C are finished.
Calculate the minimum time to complete the project.
Answer
Write down the minimum time to complete the project.
Answer
Task D takes hours and starts once both B and C are finished.
Calculate the minimum time to complete all the tasks.
Answer
A factory produces cans of tinned beans.
The table shows the list of tasks and the time taken to complete them.
| Task | Detail | Preceding task | Time (seconds) |
|---|---|---|---|
| A | Boil beans to cook them | C | 500 |
| B | Put on lid | H, E | 3 |
| C | Blanch dried beans in water | None | 300 |
| D | Attach label | I | 5 |
| E | Put sauce in tin | F | 2 |
| F | Make the sauce | None | 900 |
| G | Put in box | D | 5 |
| H | Put beans in tin | A | 2 |
| I | Cook beans in sauce in tin | B | 300 |
(a) Complete the diagram below to show the tasks and times in the boxes.
The factory manager thinks that the whole process can be completed in less than 25 minutes.
(b) Based on the times given, is the factory manager correct?
Use your working to justify your answer.
Answer
(a) Correctly completed diagram.
(b) Yes, it takes 20 minutes 15 seconds, which is less than 25 minutes.
Sarah wants to make chilli con carne. The table shows the list of tasks and the time taken for Sarah to complete them.
| Activity | Description | Preceding task | Time (minutes) |
|---|---|---|---|
| A | assemble ingredients | none | 3 |
| B | chop onions | A | 5 |
| C | heat pan with oil | B | 2 |
| D | fry onions in pan | C | 6 |
| E | add mince to pan and stir | D | 5 |
| F | open cans of kidney beans and tomatoes | C | 2 |
| G | drain kidney beans | F | 1 |
| H | measure water into jug | G | 1 |
| I | add spice mix to water | H | 2 |
| J | add spice mix and water to pan | E,I | 2 |
| K | add kidney beans and tomatoes and simmer | J | 35 |
| L | microwave rice | J | 3 |
| M | serve | K,L | 2 |
(a) Complete the diagram below to show the tasks and times in the boxes.
(b) Sarah claims she can make this chilli con carne in 55 minutes. Based on the times given, determine if she is correct.
Answer
(a) Diagram correctly completed based on precedents and times.
(b) No, the critical path is 60 minutes.
Kieran and Dylan decide to redesign their garden.
There are several tasks that need to be done in order to achieve this.
| Activity | Description | Preceding task | Time taken |
|---|---|---|---|
| A | lay patio | I | 5 hours |
| B | assemble furniture | A | 1 hour 30 minutes |
| C | remove decking | none | 6 hours |
| D | paint fence | G | 3 hours |
| E | lay artificial grass | I | 3 hours |
| F | remove grass | none | 2 hours |
| G | buy all materials | C, F | 45 minutes |
| H | plant patio tubs | A | 2 hours 15 minutes |
| I | roughcast wall | D | 1 hour 45 minutes |
(a) Complete the diagram to show the tasks and times in the boxes.
(b) Based on the times given, calculate the minimum time to complete all of the work.
Give your answer in hours and minutes.
Answer
(a) Completed diagram: Path follows C(6 hrs)/F(2 hrs) → G(45 mins) → D(3 hrs) → I(1 hr 45 mins) → A(5 hrs)/E(3 hrs). After A → H(2 hrs 15 mins)/B(1 hr 30 mins).
(b) 18 hours 45 minutes
John owns a bike shop and has a team of mechanics who build each new bicycle.
The table lists the tasks that need to be completed and the time required for each task.
| Task | Detail | Preceding task | Time (minutes) |
|---|---|---|---|
| A | attach bicycle to bicycle clamp stand | F | 1 |
| B | grease pedals | A | 1 |
| C | attach wheels | A | 7 |
| D | put bike on display | G, H, I, J | 2 |
| E | grease saddle post | F | 1 |
| F | remove bicycle frame and parts from box | none | 2 |
| G | insert saddle post into frame and tighten | E | 1 |
| H | install headset | A | 5 |
| I | inflate the tyres | C | 4 |
| J | attach pedals | B | 3 |
(a) Complete the diagram below by writing these tasks and times in the boxes.
John thinks that the team of mechanics will have the bike ready within 15 minutes.
(b) Determine if John is correct. Use your working to justify your answer.
Answer
(a) Completed diagram. Paths split from F(2). Top path: E(1) → G(1). Bottom paths split from A(1): H(5), C(7) → I(4), and B(1) → J(3). All lead into D(2).
(b) No, John is incorrect. It takes a minimum of 16 minutes to complete the bike (Critical path is F, A, C, I, D: 2 + 1 + 7 + 4 + 2 = 16).
A company produced the following table to show all the tasks involved in manufacturing and packaging chocolate eggs.
| Activity | Description | Preceding activity | Time (seconds) |
|---|---|---|---|
| A | Melt chocolate and stir ingredients | H | 600 |
| B | Wrap the egg | C, I | 30 |
| C | Cool the chocolate | D | 1800 |
| D | Pour chocolate into egg mould | A | 105 |
| E | Construct the cardboard box | G | 60 |
| F | Place wrapped egg into box | B, E | 45 |
| G | Print cardboard | H | 240 |
| H | Collect materials and ingredients | none | 120 |
| I | Print foil | H | 180 |
(a) Complete the diagram below to show the tasks and times.
(b) Calculate the minimum time taken to manufacture and package a chocolate egg.
Answer
(a) Correctly completed diagram.
(b) 2700 seconds