The largest sum that can obtain from both the dice is 12 (i.e. 6 + 6) when both dice shows 6. So, 13 (as the sum of both the dice) is impossible to occur.Hence,its probability is 0.

A measure of central tendency is a single value that attempts to describe a set of data by identifying the central position within that set of data. The mean, median and mode are all valid measures of central tendency, but under different conditions, some measures of central tendency become more appropriate to use than others. 

Range can be greater than, less than or equal to the mean.

For e.g.:

1. Data Set = {2,10}

Range = 8
Mean = 6
Here, range is greater than mean.

2. Data Set = {3,9}

Range = 6
Mean = 6
Here, range is equal to mean.

3. Data Set ={3,5}

Range = 2
Mean = 4
Here, range is less than mean.

1 occurs once
5 occurs once
6 occurs once
9 occurs twice
13 occurs twice
19 occurs once
34 occurs once
45 occurs once
We know that the mode of a set of observations is the observation that occurs most often.
Since 9 and 13 both occur twice, they both have the possibility of being modes.
But, the mode of the dataset is given to be 13, which means that 13 has to occur more number of times than 9.
So, the missing number is 13.