Question 14 6 pts Battery Lives: Twenty batteries were tested to see how many hours they would last. The frequency distribution is shown below. Number of Hours Frequency 1-3 4 4-6 8 7-9 5 10-12 13-15 Compute the mean and round the answer to 2 decimal places. Use the formula Efx n where f is the frequency and X is the midpoint. NOTE: You may use the 1-Var STAT function on the graphing calculator to compute the sample mean