Final answer:
The approximate model for the distribution of the mean CO level for the company's fleet can be represented by a normal distribution with a mean of 2.874 g/mi and a standard deviation of (0.7 / sqrt(70)).
Step-by-step explanation:
The distribution of mean CO levels for the company's fleet can be approximated with a normal distribution. This is because when the sample size is large (n > 30), the distribution of sample means tends to follow a normal distribution regardless of the shape of the population distribution.
In this case, the mean CO level for each car follows a normal distribution with a mean of 2.874 g/mi and a standard deviation of 0.7 g/mi. Since the company has 70 cars in its fleet, the mean CO level for the company's fleet (yˉ) will also follow a normal distribution.
The mean of the distribution of yˉ will be the same as the mean of the individual car distribution, which is 2.874 g/mi. The standard deviation of the distribution of yˉ can be calculated by dividing the standard deviation of the individual car distribution by the square root of the sample size (70), which is (0.7 / sqrt(70)). Therefore, the approximate model for the distribution of yˉ is a normal distribution with a mean of 2.874 g/mi and a standard deviation of (0.7 / sqrt(70)).