The delivery plan is missing, the van is almost here, and 120 supply kits are waiting to be packed. In this math mystery for students, you’ll use the clues to rule out a plan that cannot work. Then you’ll decide which of the remaining plans is best.
There may be more than one answer you can defend. The strongest answer will use accurate math and explain whyyour choice makes sense.
The Case
Students assembled 120 supply kits for a community event. Every kit must go in a box, and every box must be filled to its listed capacity.
The delivery van can carry no more than 12 boxes in one trip. The driver will arrive in 25 minutes, and volunteers need 2 minutes to load each box. The school can spend no more than $40 on boxes.
Three box types are available:
| Box type | Kits per box | Cost per box |
|---|---|---|
| A | 12 | $4.00 |
| B | 10 | $3.00 |
| C | 8 | $2.50 |
A note beside the supply cart reads:
“Choose one box type. Pack all 120 kits. Make one trip.”
The person who wrote the original delivery plan is gone for the day. Now the volunteers are looking to you for a decision.
Investigate the Clues
Check each box type before choosing. You may calculate on paper, but write your answer and reasoning in the comments.
For each type, find:
- The number of boxes needed to hold 120 kits
- The total cost of those boxes
- The time needed to load them
- Whether they fit in the van for one trip
A plan works only if it meets all four rules: it carries every kit, uses no more than 12 boxes, takes no more than 25 minutes to load, and costs no more than $40.
Solve the Mystery: Which Plan Is Best?
First, rule out any box type that breaks a rule. Then choose the best plan from the options that remain.
What matters more for this delivery: spending less money or finishing the loading sooner? Neither priority is automatically wrong. Your answer depends on which one you choose and how well you defend it.
Think about this question before you post:
If a classmate chose a different box type, what might they value more than you do?
Post Your Answer
Write one comment that explains your decision. Include your box choice, your calculations, the reason you rejected any plan that cannot work, and the priority that guided your final choice.
You can use this frame:
I would choose Box ___ because ___. We need ___ boxes to hold 120 kits because ___. The boxes would cost ___ and take ___ minutes to load. Box ___ cannot work because ___. Someone might choose Box ___ instead if they care more about ___.
Show how you got your numbers. A box letter alone does not explain your thinking.
Reply to at Least Three Classmates
After posting, read your classmates’ ideas and reply to at least three different people. In each reply, refer to a specific calculation or reason they gave. Add a question, compare their choice with yours, or explain how their thinking changed your mind.
These sentence frames can help:
- “I agree with your choice of Box ___ because your calculation shows ___. I also noticed ___.”
- “I chose a different box because I prioritized ___. Why did you decide that ___ mattered most?”
- “Your plan meets the ___ rule because ___. Did you also check the ___ rule?”
- “We calculated different costs. I got ___ × ___ = ___. Can you show me how you got yours?”
- “Your explanation made me reconsider ___. I still choose ___ because ___.”
It is okay to disagree. Be respectful, check the math, and explain your idea clearly.
Before You Submit
Read your comment one last time. Can someone follow your calculations? Does your plan meet every rule? Have you explained why your choice is best from your perspective?
Once you have posted your answer, return to the discussion and reply thoughtfully to at least three classmates. The mystery becomes more interesting when you see how someone else can use the same clues to make a different, well-supported decision.
