Step-by-step explanation:
1.
the sample space is a list of all possible outcomes.
how many different possible outcomes do we have ?
well, 3 coins, each with 2 possibilities (h/t - heads or tails).
that means
2×2×2 = 2³ = 8
and so, the list is
h h h
h h t
h t h
h t t
t h h
t h t
t t h
t t t
2.
well, from our list, all options that contain 2 or 3 t (tails).
these are
h t t
t h t
t t h
t t t
that means 4 possible outcomes out of the total 8 representing the event "at least 2 tails".
3.
a probability is always "desired cases / total possible cases".
so, in our case, to get at least 2 tails we have 4 desired cases or possible outcomes. out of 8 total possible outcomes.
therefore, the probability is
4/8 = 1/2 = 0.5
so, is there still something unclear ? please let me know.
this was a really plain and simple problem, which I guess nobody thought you cannot solve on your own, once you put at least a little bit of thought to it.
if not, you need some more explanation about the basics. so, again, please let me know.
