Question 611373
<font face="Times New Roman" size="+2">


Answer b would be correct if you put the first one you picked back into the mix and then picked the second one allowing for the possibility that both choices would be the same person.  Since that is a ludicrous idea for choosing two representatives, we have to assume non-replacement, and therefore dependent probability.


The probability of the first selection being a girl is indeed 1/2, but once a girl has been selected for the first representative, there are now only 39 girls left in a total population of 79 students.  Hence, the probability of picking a girl on the second draw is reduced to 39/79.  The probablity of both events, i.e. girl on first draw and girl on second draw is the product of the two probabilities, 1/2 times 39/79.  You can do your own arithmetic.


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
<div style="text-align:center"><a href="http://outcampaign.org/" target="_blank"><img src="http://cdn.cloudfiles.mosso.com/c116811/scarlet_A.png" border="0" alt="The Out Campaign: Scarlet Letter of Atheism" width="143" height="122" /></a></div>
</font>