Question 1195437
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<pre>

The "base" time interval is  18-11 = 7 minutes long.


The working interval is 17-15 = 2 minutes long.


Since the time is uniformly distributed, the answer to the problem's question is this ratio

    P = {{{working_time_interval/base_time_interval}}} = {{{2/7}}}.    <U>ANSWER</U>
</pre>

Solved.