3. A regional hospital is considering the parchase of a helicopter to transport critical patients, The relative frequency of z, the mumber of times the helicopter is used to transport critical patients cach month, is derived for a similarly sizel lospital and is given in the probability distribution below. 21 Piz) 0.15 0.20 0.34 0.19 0.00 0.05 0.01 (a) What is the probability that the belicopter ia not used at all during a month to transport critical patienta? (b) What is the probability that the helicopter is used at lenst 3 times during a month to transport eritical patients? (e) What is the average number of times the helicopter will be used during a month to transport critical patients? What is the standard deviaticon?