<PRE><B>Question 1131491</B>
.
&lt;pre&gt;
6 break-downs every four weeks = 6 break-downs every 28 days = {{{6/7}}} break-downs every 4 days  ====&gt;  


the probability &lt;U&gt;do not have a break-down in 4 days&lt;/U&gt; is the &lt;U&gt;COMPLEMENT&lt;/U&gt; to {{{6/7}}} = 1 - {{{6/7}}} = {{{1/7}}}.      &lt;U&gt;ANSWER&lt;/U&gt;
&lt;/pre&gt;

Solved.


</PRE>