Part-time jobs. Many students across the world take up part-time jobs, ranging from a few hours per week (for pocket money) to more intensive jobs (to partially finance their studies). A sample of 55 students with part-time jobs studying at a Dutch business school showed a mean salary of €1,200 with a sample standard deviation of €200.

a) Find a 95% confidence interval for the mean salary.

b) What assumptions have you made in this inference? Do you think the appropriate conditions have been satisfied?

c) Explain what your interval means and provide an example of what it does not mean.