# statistics; very basic

• Dec 8th 2007, 10:00 AM
0123
statistics; very basic
Suppose that you have a fair coin, and you label the head side 1 and the tail side 0. Now, fake flipping the coin 2 times and write down the sampling distribution of the sample means. Repeat flipping the coin 4 times and 10 times.

What is it asking? The result in the book is

n=2 p=0.5
x P(X=x)
0 0.25
1 0.50
2 0.25

What does that mean? Thanks a lot.
• Dec 8th 2007, 10:09 AM
topsquark
Quote:

Originally Posted by 0123
Suppose that you have a fair coin, and you label the head side 1 and the tail side 0. Now, fake flipping the coin 2 times and write down the sampling distribution of the sample means. Repeat flipping the coin 4 times and 10 times.

What is it asking? The result in the book is

n=2 p=0.5
x P(X=x)
0 0.25
1 0.50
2 0.25

What does that mean? Thanks a lot.

Flipping the coin twice gives you only one possibility of getting a 0 and 0.

Flipping the coin twice gives you two possibilities of getting a 0 and 1: (0 and 1) and (1 and 0)

Flipping the coin twice gives you only one possibility of getting a 1 and a 1.

So there are 4 possible results, thus the probability of getting two 0's is 1/4, the probability of getting a 0 and a 1 is 2/4, and the probability of getting two 1's is 1/4.

Now what are all the possible results for flipping the coin 4 times? etc.

-Dan
• Dec 8th 2007, 10:27 AM
0123
Shall I use like combinations? How can I know how many combinations of 1s I can find? And what-in the previous post- then it means x=0,1,2 with written next 0.25, 0.5, 0.25
Like 2 means 0,1 and 1,0 ?

I am sorry. I am not able to understand all this stuff. Thank you for helping.