Final answer:
The best sampling technique to determine the average speed of the cars on a highway is either a systematic sample or a simple random sample, as both are likely to produce unbiased and representative data. The correct answer is option d: a or c.
Step-by-step explanation:
The best sampling technique to use for determining the average speed of the cars on a section of highway would be a systematic sample or a simple random sample. A systematic sample might involve measuring the speed of every, say, tenth car that passes a certain point on the highway. This method implies a fixed, regular interval of selection, which can reduce the potential for bias compared to some other methods.
A simple random sample would mean that each car on the highway has an equal chance of being chosen for the speed measurement, which might involve using a random number generator to select specific cars. This would also help to ensure that the sample is representative of all cars on the highway. Both of these methods are likely to produce unbiased and representative data on the average speed of the cars. Whereas a convenience sample would be biased since it involves sampling only the cars that are convenient for the researcher to measure, which might not be representative of the whole population of cars on the highway. Therefore, choices a) or c) would be appropriate here.