Unit 8 · Rates and Ratios
Car Park Costs — Split at the 5 pm Boundary
Lesson 1 of 3
A car park charges $2.25/hr before 5 pm and $1.00/hr after. Coen parks from 3 pm to 9 pm. The price changes in the middle of his visit — so split the stay at 1700, calculate each chunk separately, then add.
Tiered pricing questions (different rates for different time bands) appear regularly on NSW Selective MR. The key skill is identifying where the price boundary falls within the visit and splitting the duration accordingly.
The examiner tests whether students convert 12-hour to 24-hour time, identify that 1700 falls within the 1500–2100 stay, correctly split into 2 hours at $2.25 and 4 hours at $1.00, and avoid the common trap of applying the $2.25 rate to the full 6 hours (giving $13.50).
A pricing table lists different hourly rates for different time windows. A person's start and end times are given in 12-hour format. The visit spans two (or more) price windows. Students must split the visit at the boundary and calculate each segment's cost.
Best approach: Step 1: Convert all times to 24-hour format. Step 2: Find which price boundaries fall within the visit. Step 3: Split the visit at each boundary. Step 4: Multiply hours × rate for each segment. Step 5: Add the segment costs.
Question
Here are the costs for a car park:
- Between 0800 and 1700: $2.25 per hour
- Between 1700 and 2300: $1.00 per hour
Coen arrives at the car park at 3 pm and leaves at 9 pm on the same day.
How much does he pay for parking?
Select an answer to see the explanation.
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