Answer
No, it would not be unusual.
Work Step by Step
$P(fewer~than~16)=P(x\lt16)=P(0)+P(1)+P(2)+P(3)+P(4)+P(5)+P(6)+P(7)+P(8)+P(9)+P(10)+P(11)+P(12)+P(13)+P(14)+P(15)=0.944$
The probability that there will be more than 15 potholes over 3 miles of randomly selected highway is the complement of the probability that there will be fewer than 16 potholes over 3 miles of randomly selected highway.
Using the Complement Rule (see page 275):
$P(more~than~15)=1-P(x\lt16)=1-0.944=0.056$
$P(more~than~15)\gt0.05$. So, it is not an unusual event.
