Question

Three unbiased coins are tossed .what is the probability of getting (1) two head
(2) at least two tail
(3) exactly 3 tail
(4) at most one head
(5) at least three tail


Q.2 if alpha and beta are zeroes of the polynomial 3x^2+2x-6, find the value of (1) alpha - Berta
(2) alpha^2+ beeta^2
(3) alpha^3+beeta^3
(4) 1/alpha+ 1/ beeta




Answer those questions plzzzzzzzz
Tomorrow is my exam

Answer 1

here's the ans of 1st que ... I'll post 2nd after some time

Answer 2

total outcomes = HHH,HTH,HTT,HHT,TTT,THT,THH,TTH
P(E) = no. of events occured / total no of outcomes
1) two head - here we would count outcomes in which two heads have occured. 
 outcomes of this event = HTH,HHT,THH i.e 3 
therefore P(E) = 3/8
2) here they are saying at least two tails that means outcomes containing two tails or more than two tails.
 outcomes of this event = HTT,TTT.THT,TTH i.e. 4.
 so P(E) = 4/8 = 1/2
3) there is only one event in which three tails occured .
  outcomes of this event = TTT. 
P(E) =1/8
4) at most one head means event with one head or with no head at all.
outcomes of this event = HTT,THT,TTT,TTH .
P(E)  4/8 = 1/2
5) at least 3 tail means event with three tails or more than three tails.
 outcomes of this event = TTT
so P(E) = 1/8