Mean battery life () = 11.25 hours Standard deviation () = 2.2 hours Value we want to find the probability for (X) = 12 hours Calculate the Z-score for 12 hours: Z = (X - ) / = (12 - 11.25) / 2.2 0.341 The Z-score of 0.341 corresponds to the probability of exceeding 12 hours of battery life with heavy use. Using a standard normal distribution table or calculator, find the probability associated with this Z-score. This will give you the probability that the battery life exceeds 12 hours. Remember to round your answer to four decimal places