two numbers? 11.(4 points) A hair stylist believes the distribution of his tips is Normal, with a mean of $10.50 and a standard deviation of $6.25. What is the probability that his 15 clients this weekend will tip an average of at least $12? 12. (6 points) A company in Brampton, Ontario hopes to improve its engines, setting a goal of no more than 3% of customers using their warranty on defective engine parts. A random survey of 1200 customers found only 20 with complaints. Create a 95% confidence interval for the true level of warranty users among all customers