Answer
$P_{60}$=251 sec.
Work Step by Step
$P_{60}$ is the value where 60 % of the values are smaller than $P_{60}$. 60% of the data here is: $24\cdot0.6=14.4$, therefore $P_{60}$ is the 15th value (the first integer at least 14.4), which is 251 sec..
