Answer
$t=1.54\ h$
Work Step by Step
From tables 4-1 and 4-2:
For 100ml of ice cream, the energy content would be 110 Cal, hence for 1L: 1100 Cal.
For a 68-kg person, the energy spent jogging is 540 Cal/h, therefore for a 90kg person: 714.71 Cal/h
Thus,
$t=\frac{1100}{714.71}=1.54\ h$
