High School

1. A bricklayer earned R1,392 for a job that took 29 hours. A carpenter earned R935 for a job that took 17 hours. Who was paid at a higher rate?

2. The rate at which water comes out of a tap is 0.15 liters per second. How long will it take to fill a drum with a capacity of 30 liters?

3. Jackson goes to the local hardware store to buy paint. He finds that the paint is sold in 1-liter, 5-liter, and 20-liter tins at a cost of R52, R214, and R894, respectively. He needs 24 liters to complete his job.
a) Which size tin represents the best value?
b) What is the cheapest way to buy enough paint to get the job done?

Answer :

Certainly! Let's solve each part of the question step by step.

1. Determining Who Was Paid at a Higher Rate:

- Brick Layer:
- Earnings: R1,392
- Time: 29 hours
- Rate per hour = R1,392 ÷ 29

- Carpenter:
- Earnings: R935
- Time: 17 hours
- Rate per hour = R935 ÷ 17

By comparing the two rates calculated above, we find that the carpenter was paid at a higher rate per hour.

2. Calculating the Time to Fill a Drum:

- Tap Flow Rate: 0.15 litres per second
- Drum Capacity: 30 litres

To find out how long it takes to fill the drum, you divide the drum capacity by the flow rate:
- Time to fill = 30 litres ÷ 0.15 litres/second = 200 seconds

Therefore, it takes 200 seconds to fill the drum.

3. Evaluating Paint Costs:

- Paint Prices:
- 1 litre: R52
- 5 litres: R214
- 20 litres: R894

- Cost per litre:
- 1 litre tin: R52 per litre
- 5 litre tin: R214 ÷ 5 = R42.8 per litre
- 20 litre tin: R894 ÷ 20 = R44.7 per litre

a) Best Value Tin:
- The best value per litre is the 5-litre tin at R42.8 per litre.

b) Cheapest Way to Buy 24 Litres:
- Purchase a 20-litre tin and a 5-litre tin for a total of 25 litres, which slightly exceeds the requirement but ensures the lowest cost. The total cost is R894 (for 20 litres) + R214 (for 5 litres).
- Total cost: R1,108.

However, to strictly get exactly 24 litres at the lowest cost, it is identified that buying multiple 5-litre tins along with 1-litre tins can achieve exactly 24 litres at a lower cost:
- Three 5-litre tins plus four 1-litre tins = 15 + 4 litres
- Total cost for this combination is R3 214 + R4 52 = R1,102.

Therefore, the highest rate, time to fill, best value tin, and cheapest way cost have been determined as per the detailed explanation above.