Alex, Lizzie, Winnie, and Greg decided to randomly switch their four lunch boxes. If they each choose one of the four boxes at random, what is the probability that EXACTLY THREE of them end up with their original lunch box?

Iam so stuck. what is the worked out answer for this question?

Solve - pv + 40 < 65 for v solve 7w - 3r = 15 for r

The average number of vehicles waiting in line to enter a parking lot can be modeled by the function f left parenthesis x right x squared over 2 left parenthesis 1 minus x right parenthesis endfraction , where x is a number between 0 and 1 known as the traffic intensity. find the rate of change of the number of vehicles waiting with respect to the traffic intensity for the intensities (a) xequals0.3 and (b) xequals0.6.