Probability, Permutation and Combination

There are 2 shirts, 3 jeans, 3 socks and 2 skirts. In how many ways shopkeeper can arrange these things so that all the socks come together and all the skirts come together? 

A fair coin is flipped three times. What is the probability that the coin lands head each time?

In a box, there are 8 red, 7 blue and 6 green balls. One ball is picked up randomly. What is the probability that it is neither red nor green?

All possible three digit numbers are formed by 1, 3, 5. If one number is chosen randomly, the probability that it would be divisible by 5 is