(Maximum mark: 6] The runtime, R, of lithium batteries made by a battery manufacturing company follows a normal distribution. R is measured in hours of continuous use in a camping head lamp. The normal distribution curve of R is shown below. 82 90 98 106 114 number of hours (a) Write down the mean runtime of the batteries. The standard deviation of the runtime of the batteries is 12 hours. (b) Find the probability that 85