A company conducted a survey among 500 customers to determine their satisfaction with their recent purchase. The results showed that 300 customers were satisfied, 150 were somewhat satisfied, and 50 were unsatisfied. Using this data, answer the following:

a) Calculate the proportions and percentages of customers who were satisfied, somewhat satisfied, and unsatisfied.
b) Construct a pie chart to visually display the distribution of customer satisfaction levels.
c) Calculate the mean and standard deviation of customer satisfaction levels.
d) Construct a 95% confidence interval for the proportion of customers who were satisfied.
e) Test the hypothesis that the proportion of customers who were satisfied is equal to 0.6, using a 5% significance level.