1. Which of the following time intervals is the largest? a) 1500 minutes b) 10 hours c) 1 day.
1. To compare time intervals, it is necessary to express them in units of the same denomination, for example, in hours:
$1500: 60=25$ (hours);

1 day $=24$ hours.

Thus, the greatest time interval is 1500 minutes.

Answer: the greatest time interval is 1500 minutes.