General Probabilty Questions

[WSOPwinner10]

1st Question:
This question is stupid. Let's say you are a 1/6 shot to pull a red marble out of a bag of 5 blue marbles and 1 red marble. What are the odds you pull at least one red marble out if you get two tries. So, you draw the first try. IF you get a red marble, you don't need to do the second trial - you already got your red marble. If you don't draw a red marble, you replace your blue marble into the bag and redraw. Are the chances you draw a red marble if you draw two times just 2/6 = 1/3?

2nd Question:
This is a question I would love to have answered. I would love the formula if possible also. Let's say you have a quarter. The most probable outcome, if you flip it ten times, is 5 heads and 5 tails. However, what are the odds that this actually happens.

A similar situation: You have a quarter. You flip it 100 times. What are the odds you land 60 heads and 40 tails.

I hope I made that question clear, as that problem has been bugging me for a while.


Thanks in advanced