# Rolling a pair of dice 20 times

1. Mar 31, 2013

### Science4ver

1. The problem statement, all variables and given/known data

I have math experiment where I roll a pair of honest dice 20 times.

The results are:

2,3,4,4,5,5,6,6,6,7,7,7,7,7,9,9,9,10,10,11

write a frequency table of the outcome of the dice roll with respect to size:

2,3,4,5,6,7,8,9,10,11,12

Firstly there must 36 possible outcomes since there two dice with 6 sides.

This gives me a frequency table which looks as follows:

x P(x)

2 1/36

3 1/36

4 2/36

5 2/36

6 3/36

7 5/36

8 0

9 3/36

10 2/36

11 1/36

12 0

Is this correct? By why doesn't the frequencies add up to 100%?? Is it because I only role the dice 20 times?

2. Mar 31, 2013

### Ray Vickson

Dividing by 36 would be correct if you rolled the dice 36 times---but you didn't.

3. Mar 31, 2013

### Science4ver

So I just exchange 36 with 20?

4. Mar 31, 2013

### Ray Vickson

What do YOU think?

5. Mar 31, 2013

### Science4ver

yes because I roll the dice 20 times and not 36.

6. Mar 31, 2013

Right!