Question 1132477
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<U>ANSWER</U>.  &nbsp;&nbsp;The probability is  &nbsp;&nbsp;{{{(10^4-9^4)/10^4}}} = 0.3439 = 34.39%.



<U>SOLUTION</U>


<pre>
{{{10^4}}}  is the number of all possible phone numbers consisting of 4 digits from 0 to 9 inclusively.


{{{9^4}}}  is the number of all possible phone numbers consisting of 4 digits from 1 to 9 inclusively  
     (that do not include  0 (zero) among the 4 digits).


The difference  {{{10^4}}} - {{{9^4}}} is the number of those 4 digit phone numbers that include at least one 0 (zero).


The ratio  {{{(10^4-9^4)/10^4}}}  is the probability you are looking for.
</pre>

Solved, &nbsp;explained and completed.