Answer
There are necessary 1.8h of swimming to burn off the kilocalories in this meal.
Work Step by Step
According to the Table 3.10 (Page 73), a 70.0 kg person, while swimming, burns 500 kcal per hour. We can use this as a conversion factor.
As we have calculated in 3.62b, the total kilocalories in this meal is equal to 920 kcal.
$920 kcal \times \frac{1h}{500kcal} = 1.84 h$
Rounding that value to the correct number of significant figures: $1.8h$