Bonjour je ne comprend pas cet exercice pourriez vous m'aidez svp

Tom wants to order tickets online so that he and three of his friends can go to a water park the cost of the tickets is 16.00 per person there is also a 2.50 one-time service fee for ordering tickets online write an expression in term of n that represents the cost for n ordering tickets online

Complex numbers multiply √-4 * √-25 and show all intermediate steps. alternative notation is sqrt(-4) * sqrt(-25).

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?