Solve the Quiz

I got this "pure logic" questions from my EF Teacher, I won't give the answer until .....IDK, I'm not sure. Just solve it out :) And no..protest

1. A logician with some time to kill in a small town decided to have his hair cut. the town only had two barbers, each with his own shop. The logician glanced into one shop and saw that is was extremely untidy. The barber needed a shave, his clothes were unkempt, his hair was badly cut. The other shop was extremely neat. The barber was freshly shaved and spotlessly dressed, his hair neatly trimmed. The logician returned to the first shop for his haircut. Why?
2. A secretary types four letters to four people and addresses the four envelopes. If she inserts the letters at random, each in a different envelope, what is the probability that exactly three letters will go into the right envelopes?
3. (easy one) If you took three apples from a basket that held 13 apples, how many apples would you have?
4. (easiest one) A chemist discovered that a certain chemical reaction took 80 minutes when he wore a tweed jacket. When he was not wearing the jacket, the same reaction always took an hour and 20 minutes. Explain

Actually there's 8 question, but the other agak sedikit maksa hehehe.