My son is doing this in 6th grade math class. Mr. Weiss started painting the kitchen at 8:45 am and finished painting at 12:00 pm. About how many hours elapsed between the time he started painting and the time he finished painting the kitchen? Answers are 2h, 3h, 4h, and 5h. He knows that there is 3 hours and 15 minutes but is not sure when asking about how many hours does he round up to 4 hours or keep it at 3 hours?

He rounds down to 3 hours since 15 minutes is less than half an hour.

To determine how many hours elapsed between 8:45 am and 12:00 pm, we need to find the difference in hours. Here's how you can calculate it:

Step 1: Convert the starting and ending times to a 24-hour format for easier calculation.
- 8:45 am (starting time) is equivalent to 08:45 in the 24-hour format.
- 12:00 pm (finishing time) is equivalent to 12:00 in the 24-hour format.

Step 2: Calculate the elapsed time in hours.
- Subtract the starting time from the finishing time: 12:00 - 08:45 = 3 hours and 15 minutes.

Now, to answer your specific question about rounding up or keeping it at 3 hours, it depends on the rounding convention being used. Commonly, if the minutes are 0-30, it is rounded down, and if the minutes are 31-59, it is rounded up. In this case, since there are 15 minutes, which is less than 30 minutes, you would typically round down.

Therefore, the elapsed time would be rounded down to 3 hours in this situation.