Answer
$x \lt73.5$
Work Step by Step
$74, 79, 71.5, 81, 73, 76, 78, 71, 72, 73.5$
$71, 71.5, 72, 73, 73.5, 74, 76, 78, 79, 81$
$71, 71.5, 72, 73, 73.5, 74, 78, 79, 81$ with one unknown height
Since 73.5 is the 60th percentile, the unknown height must be less than 73.5