Answer:
d. Ore treated with the new process.
Step-by-step explanation:
This is a common practice in statistics, in which we use a sample of a population to infer something about the entire population. We should use a sample of 100.
For example, if we want to know the proportion of residents of Buffalo, New York, who are Bills fans, we are going to take a sample of like, 100 residents, and then use this to estimate for the entire city.
In this problem, we have that:
A new process that is supposed to increase the recovered amount is being tested. In a simple random sample of 100 batches of ore, an average of 42 pounds per ton were recovered using the new process.
So the population of interest is the ore treated with new process. We use a sample of 100 to gather information about the entire population.
So the correct answer is:
d. Ore treated with the new process.