Question 1044878
<pre><b>Rule of thumb:

1. "and" usually means to multiply probabilities
2. "or" usually means to add probabilities

{{{P(

matrix(1,7,

(matrix(5,1,first,coin,toss,is,heads)),
and,
(matrix(5,1,second,coin,toss,is,heads)),
and,
(matrix(5,1,third,coin,toss,is,heads)),
and,
(matrix(5,1,fourth,coin,toss,is,heads))

)^"")}}}{{{""=""}}}

{{{matrix(1,7,

P(matrix(5,1,first,coin,toss,is,heads)),
""*"",
P(matrix(5,1,second,coin,toss,is,heads)),
""*"",
P(matrix(5,1,third,coin,toss,is,heads)),
""*"",
P(matrix(5,1,fourth,coin,toss,is,heads)))}}}{{{""=""}}}

{{{matrix(1,7,
1/2,
""*"",
1/2,
""*"",
1/2,
""*"",
1/2)}}}{{{""=""}}}{{{1/16}}}

Therefore,

{{{P(

matrix(13,1,
there, will, be, at, least, one, tail, out, of, the, four, coin, tosses))}}}{{{""=""}}}{{{1-1/16}}}{{{""=""}}}{{{16/16-1/16}}}{{{""=""}}}{{{15/16}}}

Edwin</pre></b>