16.1 - Determine the missing probability
0.04
All probabilities must add up to 1.00 (or 100%)

16.2 - Calculate expected value and standard deviation, then interpret in context
E(Red Lights) = 0*.02 + 1*.07 + 2*.15 + ... + 6*.01 = 2.93
Over the long run, the average number of red lights hit on each drive to school will be 2.93

sigma (Red Lights) = 1.01
Var(Red Lights) = (1.01)^2
Over the long run, the amount of variability (standard deviation) in number of red lights hit on a drive to school is 1.01

16.3 - Determine new E(X) and sigma(X) when adding by a constant or multiplying by a constant
If wait time is 3 minutes at each red light, then multiply all red light values by 3...
Wait Time = 3*Red Lights

E(Wait Time) = E(3*Red Lights) = 3*E(Red Lights) = 3*2.93 =
sigma(Wait Time) = E(3*Red Lights) = 3*E(Red Lights) = 3*1.01 =
Var(Wait Time) = (3*1.01)^2

16.4 - Variances Add
Difference In Wait Times = Your Time - Friend's Time
E(Difference In Wait Times) = E(Your Time) - E(Friend's Time)

Var(Difference In Wait Times) = Var(Your Time) + Var(Friend's Time) <<Variances Add...ALWAYS>>
sigma(Wait Time) = sqrt(Var(Difference In Wait Times))