GRADE 10 INFORMAL TEST: SECION 6 RATES. Questions 1-7.2 dealing with rates and unit ratios.

Here are the solutions to your questions:

1. To determine the total cost, multiply the quantity of petrol by the price per litre.

$$\text{Total Cost} = 25 \text{ litres} \times \text{R}25.39/\text{litre}$$ $$\text{Total Cost} = \text{R}634.75$$

It will cost R634.75 to put 25 litres of petrol.

2. To calculate the call cost, multiply the rate per minute by the duration of the call.

$$\text{Call Cost} = \text{R}2.25/\text{minute} \times 3\frac{1}{2} \text{ minutes}$$ $$\text{Call Cost} = \text{R}2.25/\text{minute} \times 3.5 \text{ minutes}$$ $$\text{Call Cost} = \text{R}7.875$$ $$\text{Call Cost} \approx \text{R}7.88$$

A $3\frac{1}{2}$ minute call will cost R7.88.

3. First, convert the mass of potatoes from grams to kilograms. Then, multiply by the price per kilogram.

Step 1: Convert 500 g to kg.

$$500 \text{ g} = \frac{500}{1000} \text{ kg} = 0.5 \text{ kg}$$

Step 2: Calculate the cost.

$$\text{Cost} = 0.5 \text{ kg} \times \text{R}62.00/\text{kg}$$ $$\text{Cost} = \text{R}31.00$$

Luvo will pay R31.00 for 500 g of potatoes.

4. To find the cost of each packet, divide the total cost by the number of packets.

$$\text{Cost per packet} = \frac{\text{R}230.90}{8 \text{ packets}}$$ $$\text{Cost per packet} = \text{R}28.8625$$ $$\text{Cost per packet} \approx \text{R}28.86$$

Each packet of biscuits costs R28.86.

5. To calculate the average speed, divide the total distance by the total time taken.

$$\text{Average Speed} = \frac{\text{Distance}}{\text{Time}}$$ $$\text{Average Speed} = \frac{300 \text{ km}}{3 \text{ hrs}}$$ $$\text{Average Speed} = 100 \text{ km/hr}$$

Sipho's average speed is 100 km/hr.