Please help answer these questions!

(1) In a city, the average age of a car in use is 10 years with a standard deviation of 6 years. What is the probability that a random sample of 25 cars will have an average between 8 and 11 years?

(2) An office claims that its employees commute to work an average of 9 miles daily with a standard deviation = 5 miles. A sample of 49 employees produced a sample average of 10.2 miles. At 0.05 level of significance, do you reject the office's claim?

(3) A manufacturer of light bulbs claims that its light bulbs have a mean life of 1520 hours. A consumer group believes the actual mean is smaller and challenges the manufacturer's claim. A random sample of 40 bulbs shows a mean of 1497 hours with a standard deviation = 85 hours. At 0.05 level of significance, is there evidence that the mean is smaller?

(4) A student group maintains that the average student must travel 25 minutes in order to reach the college each day. The college admissions office obtained a random sample of 28 travel times. The sample had a mean of 19.4 min with a standard deviation s = 9.6 min. At 0.01 level of significance, does the college have sufficient evidence to reject the student group's claim?

(5) You take 12 night class hours a week and believe it is too much, and that your friends are enrolled in fewer classes. Four friends selected at random give you a mean of 8 hours with a standard deviation of 4 hours. At 0.05 level of significance, are your friends taking fewer hours than you?