If we toss two coins simultaneously, then possible out comes (s), are
S = { HT, TH, HH, TT }
⇒    n( S) = 4
Let E be the favourable outcomes of getting two heads, then
E = { H H }
⇒    n(E) = 1

Therefore,   P(E) = 

Let F be the favourable outcomes of getting at least one head, then
F = { HH, HT, TH }
⇒    n(F) = 3
Therefore,   P(F) = 

Let G be the favourable outcomes of getting no head then
⇒    n (G) = 1

Therefore,   P(G) =