Answer:
[tex]\frac{1}{8}[/tex] or [tex]\frac{9}{78}[/tex]
(see explanation)
Step-by-step explanation:
This problem is asking about compound probability, what is the probability of this even happening three times in a row.
Since there are 20 boy's names and 20 girl's names in the hat, one can say that half of the names in the hat. Assume that after drawing it from the hat, the name is put back into the hat. Therefore, on each night, there is a half-chance of the event happening. To find the probability of the event, one must multiply ([tex]\frac{1}{2}[/tex]) by itself (3) times,
[tex](\frac{1}{2})(\frac{1}{2})(\frac{1}{2})\\=\frac{1}{8}[/tex]
In this case, assume that after each drawing the name is not replaced into the hat. This means that after every draw, one must subtract (1) from both the numerator and denominator of the fraction when the fraction is in the un-simplified form.
[tex](\frac{1}{2})(\frac{19}{39})(\frac{18}{38})[/tex]
Simplify,
[tex](\frac{1}{2})(\frac{19}{39})(\frac{9}{19})[/tex]
[tex]\frac{9}{78}[/tex]
