The purpose of this task is to engage students in calculating a combined probability and using this to solve a problem.

The background knowledge and skills that need to be established before and/or during this task are outlined in the diagram below:

This task may be carried out with step by step guidance, or by allowing the student to follow their own method of solution. The approach should be chosen in sympathy with students' skills and depth of understanding.

Task: Janice has an after school job, for an hour each school day. To get to the job, she parks her moped on a P60 space on the street outside. She doesn't use the nearby parking building which charges $3 for the first two hours of parking.

Using the P60 is usually fine, but she does get held up at work 2 out of every 5 days and so overstays the allowed 60 minutes on those days. There is a 25% chance on any given day, that parking wardens are around and will write a $20 fine for cars overstaying their park.

Should Janice keep risking the P60 parking, or would she save money by using the parking building?

### The procedural approach (show more)

- The student is able calculate a combined probability and use this to solve a problem, with guidance.

### The conceptual approach (show more)

- The student is able calculate a combined probability and use this to solve a problem.