Adrian exercised three days during the past week. He exercised:

- 100 minutes and 20 seconds on the first day
- 96 minutes and 25 seconds on the second day
- 103 minutes and 15 seconds on the third day

How many hours did he spend exercising during the week?

[tex]
\[
\begin{aligned}
& \text{Units of Time} \\
60 \text{ seconds (sec)} = 1 \text{ minute (min)} & \\
60 \text{ minutes} = 1 \text{ hour (hr)} & \\
24 \text{ hours} = 1 \text{ day} & \\
7 \text{ days} = 1 \text{ week} & \\
\end{aligned}
\]
[/tex]

To find out how many hours Adrian spent exercising during the past week, we'll add up the total exercise time from each day and convert that time into hours. Let's break down the process step by step:

1. Day 1:
Adrian exercised for 100 minutes and 20 seconds.
- Convert 100 minutes into seconds: [tex]$100 \times 60 = 6000$[/tex] seconds.
- Add the 20 seconds to this: [tex]$6000 + 20 = 6020$[/tex] seconds.

2. Day 2:
Adrian exercised for 96 minutes and 25 seconds.
- Convert 96 minutes into seconds: [tex]$96 \times 60 = 5760$[/tex] seconds.
- Add the 25 seconds to this: [tex]$5760 + 25 = 5785$[/tex] seconds.

3. Day 3:
Adrian exercised for 103 minutes and 15 seconds.
- Convert 103 minutes into seconds: [tex]$103 \times 60 = 6180$[/tex] seconds.
- Add the 15 seconds to this: [tex]$6180 + 15 = 6195$[/tex] seconds.

4. Total Exercise Time:
Now, add up all the seconds from the three days to find the total exercise time in seconds:
[tex]\[
6020 + 5785 + 6195 = 18000 \text{ seconds}
\][/tex]

5. Convert Total Seconds to Hours:
Since there are 3600 seconds in an hour, convert the total seconds into hours:
[tex]\[
\frac{18000}{3600} = 5 \text{ hours}
\][/tex]

Adrian spent a total of 5 hours exercising during the week.