1. There were 25 teachers in a school whose mean age was 30 years. A teacher retired at the age of 60 years and a new teacher was appointed in his place. The mean age of teachers in the school was reduced by one year. Find the age of new teacher?
2. A coin is tossed six times. Find the probability of obtaining heads and tails alternately?
3. Machine shop has eight screw machines but only three spaces available in the production area for the machines. In how many different ways can the eight machines be arranged in the three spaces available?