QUESTION 15 A certain type of engines lasts, on average, 4.0 years with a standard devlation of 0.5 year. Assuming that the engine lifetimes are normally distributed, the probability that a given machine will last less than 3.6 years is a. 0.7881 b. 0.3446 c. 0.4364 d. 0.2119

Problem 2. The service life of a battery used in a cardiac pacemaker is assumed to be normally distributed. A random sample of 10 batteries is subjected to an accelerated life test by running them continuously at an elevated temperature until failure, and the following lifetimes (in hours) are obtained: 25.5, 26.1, 26.8, 23.2, 24.2, 28.4, 25.0, 27.8, 27.3, and 25.7. a) The manufacturer wants to be certain that the mean battery life exceeds 25 h. What conclusions can be drawn from these data (use a= 0.05)? b) Construct a 95% one-sided confidence interval on mean life in the accelerated test.

Question 4 Suppose an electric-vehicle manufacturing company estimates that a driver who commutes 50 miles per day in a particular vehicle has a recharging time that has a uniformly distributed between 80 and 110 minutes. What is the expected recharging time in minutes? (Enter your answer with no decimal places)

QUESTION 3 A certain type of engines lasts, on average, 4 years with a standard deviation of 1.4 years. Assuming that the engine lifetimes are normally distributed, the probability that a given machine will last less than 3.5 years is O 0.1406 0.3594 O 0.6406