Interval Frequency The lives (in hours of continuous use) of 100 randomly selected 6.95 - 7.45 2 flashlight batteries are: 7.45-7.95 10 7.95 -8.45 21 8.45 - 8.95 35 8.95 - 9.45 19 9.45 - 9.95 11 9.95 - 10.45 2 a. Find the mean of the battery lives. 8.70 hrs (Type an integer or a decimal. Round to two decimal places.) b. Find the standard deviation of the battery lives. hrs (Type an integer or a decimal. Round to two decimal places.)