Imagine there are four friends, and they want to cross a bridge together, but the bridge is old and can only hold two people at a time. Also, it's very dark at night, so they have only one flashlight to see where they're going.

Now, these four friends are all different when it comes to how fast they can walk:

1. One friend is super fast and can cross the bridge in just 1 minute.
2. Another friend is not as fast, and it takes them 2 minutes to cross.
3. The third friend is a bit slower and needs 5 minutes to get across.
4. The last friend is the slowest and takes a long 10 minutes to cross.

Here's how they can all get across the bridge as quickly as possible:

1. The two fastest friends, the 1-minute and 2-minute ones, go together first. Since they're fast, they'll use just 2 minutes because they walk at the slower person's pace.

2. Now, the super-fast friend with the 1-minute time goes back to the starting side with the flashlight. This takes 1 more minute.

3. Next, the two slowest friends, the 5-minute and 10-minute ones, go together. This time, they use 10 minutes because they walk at the slower person's pace.

4. The 2-minute friend goes back to the starting side with the flashlight, which takes 2 more minutes.

5. Finally, the two fastest friends, the 1-minute and 2-minute ones, go together again for the last time. It takes them just 2 minutes.

Now, everyone is safely on the other side of the bridge! The fastest way for all four friends to cross was to use a total of 2 + 1 + 10 + 2 + 2 = 17 minutes.

So, by taking turns and being very careful, they all crossed the bridge together in the shortest time possible, which is 17 minutes.

Great teamwork, right? They made it across the bridge safely and as quickly as they could!