Question 1152176
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<pre>

There are  N = {{{C[5000]^4}}}  ways to select 4 CDs from the set of 5000 CDs without replacement.

It is the whole space of samples in this problem.


Next, from the condition, every 4 CDs that pass testing, belong to the subset of 5000-100 = 4900 good CDs.


There are  n = {{{C[4900]^4}}}  ways to select 4 CDs from this set of 4900 CDs.


Therefore, the probability under the question is the ratio 

    {{{n/N}}} = {{{C[4900]^4/C[5000]^4}}} = {{{(4900*4899*4898*4897)/(5000*4999*4988*4987)}}} = 0.922346.      <U>ANSWER</U>



Another way to solve the problem is to use the formula

    P = {{{(4900/5000)*(4899/4999)*(4898/4998)*(4897/4997)}}} 

which is self-explanatory and gives <U>the same result</U>  P = 0.922346.  
</pre>

Solved.