Question

Graph All the plans on the graph provided. Your graph should include talk times between 0 and 200 minutes.

2. Was your plan in part B an example of direct variation (the plan depended only on the time spent talking) or a partial variation? (the plan depended on the time spent talking and an initial cost). 3. Which Plan best for you? Was this the same as your hypothesis? 4. Which plan had the highest rate of change? Which plan has the lowest slope?
5. Using your graph, which plan would be best if you talked for 200 minutes? 6. When is the Rogers My5 plan better than the Telus prepaid plan? 7. Which plans are an example of direct variation? 8. Come up with at least 3 other things that need to be considered when choosing your cell phone plan (aside from cost per minute talking), and explain why these are important to you.

Answer 1

I'll do the first five problems to get you started.

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Problem 1

The graph is shown below in the attached image.

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Problem 2

The plan chosen was Public Mobile, which offered $24 per month for unlimited minutes. This plan does not depend on the number of minutes, so this is not a direct variation. It's also not a partial variation either since the cost doesn't vary (ie change) at all. The monthly cost is fixed at $24 per month.

Even at 200 minutes, this is the cheapest plan as mentioned in the other chart I posted. You can determine this by plugging x = 200 into each equation described earlier. You should find that Public Mobile still gives the cheapest rate. The graph done in problem 1 visually verifies this. The gray line y = 24 is below each of the other lines when x = 200.

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Problem 3

The best plan is still Public Mobile when x = 1800 minutes per month.

Any x value such that x > 140 will also have Public Mobile be the best plan.

When we get to x = 140 is when this isn't the best plan and instead Bell is the better plan to go with. Note the purple line y = 0.10x+10 is below the gray line y = 24 for values x < 140. This visually shows us that Bell is cheaper compared to Public Mobile.

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Problem 4

The plan with the greatest rate of change is Telus. This is because y = 0.35x has the largest slope of 0.35

The rate of change is the charge per minute.

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Problem 5

If you talked for 200 minutes, then Public Mobile is the best plan. This is because the gray line y = 24 is below any other line when we have x = 200.