What is two days after the day after the day before yesterday?

Mary’s father has 5 daughters – Nana, Nene, Nini, Nono. What is the name of the fifth daughter?

You have three boxes. One has only red marbles, one has only blue marbles and the third has an equal number of red and blue marbles. The labels on the boxes have intentionally been switched so that each box is now marked incorrectly.

Your job is to relabel the boxes correctly. Of course you could just look in the boxes to find out which labels match, but can you do it without looking into each box? Reach into any one of the boxes and select one marble. Can you now correctly label all three boxes? If not, select a second marble from any box. What is the fewest number of marbles you need to inspect in order to correctly label each box?

At the scene of a heinous crime, five suspects, one of whom is the guilty party, are being interrogated by a detective. Each of the suspects gives one statement and it later transpires that just three of these statements are correct.

These are the statements:
Uncle Jack: Uncle Jim committed the murder
Aunt Mary: I did not do it
Cousin Stewart: It was not Cousin Margaret
Uncle Jim: Uncle Jack is lying when he says I did it
Cousin Margaret: Aunt Mary is telling the truth

Who committed the murder?