Please look at the picture and answer.

1. An airline tracked its flights to determine how early or late they were. The chart summarizes their findings on a specific day. (Note that a negative time means the flight was early.) Class Boundaries Time (min) Frequency [-15, -5) 6 [-5, 5) 23 [5, 15) 31 [15, 25) 25 [25, 35) 13 [35, 45) 3 [45, 55) 4 [55, 65) 1 a) Determine the mean, variance, and standard deviation. [6 marks] Mean: Variance: Standard Deviation: b) Determine the median and mode. [4 marks]