Question 156690
4) Correct.




5) 

a)  With Replacement


<pre>

                   # of red marbles      12
P(First is red) = ------------------ =  ----
                  total # of marbles     25


</pre>


Since you are replacing the marble (ie putting it back), this means that the total number of marbles stays the same



<pre>

                      # of black marbles      13
P(Second is black) = ------------------ =  -------
                     total # of marbles       25


</pre>



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b) Without Replacement

<pre>

                   # of red marbles      12
P(First is red) = ------------------ =  ----
                  total # of marbles     25


</pre>



Now since you are <b>NOT</b> replacing the marble, this means that the total number of marbles will go from 25 to 24


<pre>

                      # of black marbles            13         13
P(Second is black) = ----------------------    = --------- =  -----
                     total # of marbles - 1         25-1       24


</pre>