4. A personal fitness trainers fee is $75 per hour. Based on her past records, she determined that 20% of her clients required only one hour of training, 65% required two hours and the rest required 3 hours of training. She did not have a client that required more than 3 hours of training. Records also showed that she incurred a cost of $10 for every hour that she spent with a client.

a) Write down the probability distribution of her net profit (profit= revenue cost). b) In one week, she sees 8 clients. What total profit can she expect to earn for this week? Explain your answer.