Question 286762
<pre><font size = 4 color = "indigo"><b>
P(at least one head) = 1 - P(no heads) =

1 - P(tails 1st AND tails 2nd AND tails 3rd) =

"AND" indicates multiplication:

1 - P(tails 1st)*P(tails 2nd)*P(tails 3rd) =

{{{1-(1/2)(1/2)(1/2)=1-1/8=7/8}}}

choice (a)

Edwin</pre>