Two coins are tossed simultaneously. Find the probability of getting

(i) two heads

(ii) at least one head

(i) Probability of getting two heads = 0.5*0.5 = 0.25

(Here we multiply the probability of getting a head by the probability of getting a head)

(ii) Probability of getting at least one head = 0.5*0.5 + 0.5*0.5 + 0.5*0.5 = 0.75

(Here we add the probability of getting a head and a head to the probability of getting a head and then a tail and then add the probability of getting a tail and then a head)

The second way to do this is to subtract the probability of not getting any heads (ie. getting a tail and a tail) from 1:

1 - 0.5*0.5

= 1 - 0.25

= 0.75