A mobile phone plan costs R20 per month plus R2.50 per minute. Calculate the total cost for various minutes and describe the relationship.

1.1 To complete the table, we use the formula: Total Cost (R) = Fixed monthly fee + (Cost per minute $\times$ Minutes).
Given: Fixed monthly fee = R20, Cost per minute = R2.50.
So, Total Cost (R) = $20 + (2.50 \times M)$.

2.1 Describe how the total cost changes as minutes increase.
As the number of minutes increases, the total cost also increases. For every additional minute, the total cost increases by a constant amount.

2.2 What is the cost per additional minute?
The cost per additional minute is given in the problem description.
The cost per additional minute is $\boxed{\text{R2.50}}$.

2.3 Is the relationship increasing or decreasing? Explain.
The relationship is increasing. As the number of minutes used increases, the total cost also increases because there is a positive cost associated with each additional minute.

3.1 Draw a graph showing the relationship between minutes and total cost.
I cannot draw a graph directly, but here are the instructions and points you need to plot:

• Title: Total Cost vs. Minutes for a Prepaid Plan
• Correct labels:
  • X-axis: Minutes (M)
  • Y-axis: Total Cost (R)
• Suitable scale: Choose a scale that allows all points to fit comfortably on your graph paper. For example, for minutes, you could use 1 unit = 5 minutes. For total cost, you could use 1 unit = R10.
• At least 5 plotted points: Use the following points from the completed table:
  • $(0, 20)$
  • $(5, 32.50)$
  • $(10, 45)$
  • $(15, 57.50)$
  • $(20, 70)$
  • $(30, 95)$
• Straight line: Connect the plotted points with a straight line, as this is a linear relationship.