Give me 3 logical challenges to submit to my friends
Here are three logical challenges you can submit to your friends:

1. The Hat Riddle: This classic riddle involves placing a hat on each person's head and having them guess the color of their own hat. You can find the full riddle and rules online. The challenge is to figure out a strategy that allows the group to guess as many correct colors as possible.

2. The Monty Hall Problem: This probability puzzle involves a game show where a contestant is asked to choose between three doors, behind one of which is a prize, and behind the other two are goats. After the contestant chooses a door, the host (who knows what is behind each door) opens one of the remaining doors to reveal a goat. The contestant is then given the option to switch their choice to the other unopened door or stick with their original choice. The challenge is to figure out whether it is more advantageous to switch or stick with the original choice.

3. The River Crossing Problem: This problem involves a farmer who needs to transport a fox, a chicken, and a bag of grain across a river, but can only take one of them at a time in his boat. The challenge is to figure out a sequence of trips that gets all three items to the other side of the river without the fox eating the chicken or the chicken eating the grain. There are variations of this puzzle with different objects and constraints, so you can choose one that suits your group.
Can you give me the solutions to those problems?
Sure. Here are the solutions:

The Hat Riddle: The strategy to guessing the colors correctly is for each person to look at the colors of the hats on the other people's heads and count how many hats of each color there are. If the count is an even number, they guess that their hat is a different color than the majority. If the count is an odd number, they guess that their hat is the same color as the majority. With this strategy, at least half of the group will guess correctly.

The Monty Hall Problem: It is more advantageous to switch doors after the host opens one of the remaining doors to reveal a goat. This is because there is a 2/3 probability that the prize is behind one of the other unopened doors, and switching doors increases the chances of winning to 2/3.

The River Crossing Problem: One solution to this puzzle is:

1. The farmer takes the chicken across the river and leaves it on the other side.
2. The farmer goes back and takes the fox across the river, but brings the chicken back with him to the original side.
3. The farmer takes the grain across the river and leaves it on the other side.
4. The farmer goes back and takes the chicken across the river to join the fox and grain on the other side.