Answer:
1, ,
.
Step-by-step explanation:
probability =
Total number of persons in the party = n
a) Pr ( every person gets their phone back) = Pr (each person picks his phone ) multiplied by number of person
= × n = 1.
No of first m persons to pick = m
No of last m persons to pick = 1 - m
b) Pr (first m persons to pick each gets their phones back) =
c) Pr( first m persons get a phone belonging to last m persons) =