Brain teaser Answers.
1. If 1.5 hens lay 1.5 eggs in 1.5 days, it must be that one hen would lay one egg in the same time period: 1.5 days. Now, if one hen lays one egg in 1.5 days, it means that one hen would lay only ⅔'s of an egg in one day. So the answer is ⅔'s of an egg.
2. Flip switch number 1 and wait a few minutes. Flip switch number 1 back to its original position, and then immediately flip switch number two Open the door. If the light is on, then switch number 2 controls it. If the light is off, then go and feel the bulb with your hand. If the bulb is hot, the switch number 1 controls it, and if the bulb is cold, then switch number 3, the one you did not touch, controls it.
3. The key to solving this riddle is realizing that Adam played scissors six times. Because there were no ties, that means Eve didn't play scissors in any of those six games. Now look at the various hands Eve did play. Because she played scissors four times, and none of those could line up with one of the six times Adam played scissors, she must have played all six of her other hands on Adam's six scissors. Therefore, six of the games, not necessarily in order, were as follows: Adam: scissors vs. Eve: rock [Winner: Eve]
Adam: scissors vs. Eve: rock [Winner: Eve]
Adam: scissors vs. Eve: paper [Winner: Adam]
Adam: scissors vs. Eve: paper [Winner: Adam]
Adam: scissors vs. Eve: paper [Winner: Adam]
Adam: scissors vs. Eve: paper [Winner: Adam]
Now look at what is left over. We see that Eve has only scissors left. Therefore, the other four games are:
Adam: rock vs. Eve: scissors [Winner: Adam]
Adam: rock vs. Eve: scissors [Winner: Adam]
Adam: rock vs. Eve: scissors [Winner: Adam]
Adam: paper vs. Eve: scissors [Winner: Eve]
Tally it all up, and Adam wins, 7 to 3.
4. First, the farmer must take the chicken across the river, leaving the fox and corn alone together on the starting side. Then, the farmer goes back and gets the fox. When he takes the fox across the river, instead of leaving the fox alone with the chicken, he swaps them out and takes the chicken back to the starting side. He then swaps the chicken out for the corn and brings it across, leaving the fox and corn alone on the far side. Finally, he goes back to get the chicken, bringing all three items across the river without letting anything eat anything else.
5. The only way to be absolutely certain you will know which crates contain which fruits is if you ask your co-worker to pull a fruit out of the crate that is labeled "A+O" to show to you. You know the crate is incorrectly labeled, so it doesn't have both apples and oranges in it. So if he pulls an apple out of the "A+O" crate, it has apples in it. If he pulls an orange out, it has oranges. Let's say he pulls an apple out of the "A+O" crate, so you know it has apples in it. Now you know that the crate labeled "O" doesn't have just apples in it, because the "A+O" crate is the one with just apples in it, and you know the "O" crate doesn't have just oranges in it, because it is incorrectly labeled. So the "O" crate must have both apples and oranges in it, which leaves the "A" crate with just oranges.