solve........

Some manufacturers claim that non-hybrid sedan cars have a lower mean miles-per-gallon (mpg) than hybrid ones. Suppose that consumers test 21 hybrid sedans and get a mean of 30 mpg with a standard deviation of 6 mpg. Thirty-one non-hybrid sedans get a mean of 21 mpg with a standard deviation of three mpg. Suppose that the population standard deviations are known to be six and three, respectively. Conduct a hypothesis test at the 5% level to evaluate the manufacturers claim. NOTE: If you are using a Student's t-distribution for the problem, including for paired data, you may assume that the underlying population is normally distributed. (In general, you must first prove that assumption, though.) Part (a) Part (b) State the alternative hypothesis. O Hai Hhybrid Hnon-hybrid Part (c) In words, state what your random variable Xhybrid - Xnon-hybrid represents. O Xhybrid - Xnon-hybrid represents the difference in the miles per gallon of non-hybrid and hybrid sedans. O Xhybrid - Xnon-hybrid represents the difference in the average gas mileage of a non-hybrid sedan and a hybrid sedan. O Xhybrid - Xnon-hybrid represents the average gas mileage of sedans. O Xhybrid - Xnon-hybrid represents the average difference in the miles per gallon of non-hybrid and hybrid sedans. Part (d) State the distribution to use for the test. (Round your answers to two decimal places.) Xhybrid - Xnon-hybrid