C. would be the correct device to use in trials.
But the actual probability is:
(1-1/4)^5
243/1024
(about 23.73% chance none of the five chose vanilla)
The picture is upside down my dude, delete the question, re-upload it and ill help you out.
<span>(a+b)(c+d)=ab+ad+bc+bd
(5k-4)(4k-5)=20k^2+-25k-16k+20=20k^2-41k+20
Hope this helps!</span>
