#### Answer

Not unusual.

#### Work Step by Step

If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=77.5-2\cdot11.6=54.3$
$Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=77.5+2\cdot11.6=100.7$. Here, $54.3<99<100.7$, therefore the value is not unusual, because it is between the minimum and maximum usual value mean.