When is the substitution method a better method than graphing for solving a system of linear equations?

The mean of a set of data is -3.82 and its standard deviation is 2.31. find the z score for a value of 3.99.

Read the situations in the table below. then drag a graph and equation to represent each situation. indicate whether each of the relationships is proportional or non-proportional. edit : i got the right answer its attached

Four airplanes carrying a total of 400 passengersarrive at the detroit airport. the airplanes carry, respectively,50, 80, 110, and 160 passengers.a) one of the 400 passengers is selected uniformly at random.let x denote the number of passengers that were on theairplane carrying the randomly selected passenger. find var(x)for x as given in the problemb) one of the 4 airplane drivers is also selected uniformly atrandom. let y denote the number of passengers on the chosen driver’s airplane. find var(y) for y as given in the problem