Turf order against a fixed P&C budget
The P&C has budgeted $520 to re-turf a courtyard at Kallista Primary. The courtyard is a rectangle 12.4 m by 8.6 m, but a rectangular garden bed 3.2 m by 2.5 m occupies one corner and will not be turfed. Turf is supplied in rolls measuring 1.5 m by 0.6 m at $4.20 per roll, and the supplier recommends ordering 5% extra to allow for cutting and waste. Plastic edging for the full boundary of the turfed area costs $0.85 per metre. The P&C wants the whole job done from a single order - no second delivery - and will not exceed the budget.
1. Find the area to be turfed and the length of edging required.
Read the worked answer
Area
- Whole rectangle: 12.4 × 8.6 = 106.64 m²
- Garden bed: 3.2 × 2.5 = 8.00 m²
- Turfed area: 106.64 − 8.00 = 98.64 m²
Edging The bed is cut out of a corner, so the two sides removed (3.2 m and 2.5 m) are exactly replaced by the two new inner edges - the perimeter is the same as the full rectangle:
- 2 × (12.4 + 8.6) = 42.0 m
- Edging cost: 42.0 × $0.85 = $35.70
(Check by adding the six sides: 12.4 + 8.6 + 9.2 + 2.5 + 6.1 + 3.2 = 42.0 m.)
2. Calculate the number of rolls to order with the 5% allowance and the total cost, and state the budget position.
Read the worked answer
- Area with 5% waste: 98.64 × 1.05 = 103.572 m²
- Area of one roll: 1.5 × 0.6 = 0.9 m²
- Rolls needed: 103.572 ÷ 0.9 = 115.08 → must round up: 116 rolls
- Turf cost: 116 × $4.20 = $487.20
- Plus edging $35.70 → total $522.90
This is $2.90 over the $520 budget, so the plan as stated cannot be approved.
3. Propose a way to bring the job inside $520 without a second delivery, and show the figures that justify it.
Read the worked answer
The cheapest lever is the waste allowance, since the edging length is fixed by the shape.
- Absolute minimum (no waste) is 98.64 ÷ 0.9 = 109.6 → 110 rolls, so there is room to trim.
- Try a 3% allowance: 98.64 × 1.03 = 101.60 m² → 101.60 ÷ 0.9 = 112.9 → 113 rolls
- Cost: 113 × $4.20 = $474.60; plus edging $35.70 = $510.30 - inside budget with $9.70 spare.
- Wriggle room check: 113 rolls give 101.7 m², which is 3.06 m² (3.1%) of waste - still a realistic cutting allowance for a simple rectangle-plus-notch.
So order 113 rolls, accepting a slightly leaner waste margin rather than asking for more money. Reducing edging or splitting the order is not acceptable under the P&C's conditions.