Question 1098894
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Let me re-formulate it equivalently in this simple form:



<pre>
    Of every 100 teenagers, 78 have an i-pod and 45 have both i-pod and sell phone.
</pre>


Then it is absolutely clear that the probability under the question is  &nbsp;&nbsp;{{{45/78}}}.


The equivalent formula of the Probability theory is &nbsp;&nbsp;P(A|B) = {{{P(A)/P(B)}}} = {{{0.45/0.78}}}.