A car manufacturer is interested in estimating the true mean fuel consumption in real-world city driving for one of its new models.

A car manufacturer is interested in estimating the true mean fuel consumption in real-world city driving for one of its new models.  12 new randomly selected cars are driven for a tank, and it is found that the sample mean fuel consumption is 9.4 l/100k, with a sample standard deviation of s = 0.351. Suppose the manufacturer wishes to construct a confidence interval for mu, the true mean fuel consumption for this model under these conditions. Suppose it is reasonable to assume the fuel consumption is approximately normally distributed.