very last statistics questions
The manufacturer’s recommended air pressure for a certain type of tire is 32 psi. A random sample of n=35 such tires from different cars operated by a large rental company yields a sample average pressure and sample standard deviation of 31.4 and 1.2, respectively. Does this data suggest that the average pressure for all such tires on that rental company‘s cars differs from the recommended value?
To get the p-value my teacher used the Standard normal distribution, but shouldn't we use the student t distributon, because we have sample standard deviation not the population data?