1. If two coins are tossed then find the probability of the events :
(i) at least one tail turns up
(ii) no head turns up
(iii) at the most one tail turns up
Sol. When two coins are tossed
S = { HH, HT, TH, TT }
n (S) = 4
(i) Let A be the event that atleast one tail turns up
A = { HT, TH, TT }
n (A) = 3
P (A) = n(A)/n(S)
∴ P(A) = 3/4
(ii) Let B be event that no head turns up
B = { TT }
n (B) = 1
P(B) = n(A)/n(S)
∴ P(B) = 1/4
(iii)Let C be the event that at the most one tail turns up
C = { HH, HT, TH }
n (C) = 3
P (C) = n(C)/n(S)
∴ P (C) = 3/4
