Equivalent ratios for 5:13

Just multiply 5:13 by any number
10:26
15:39
20:52
25:65
etc...

In order to the get the mean, you will have to add all of the values and then divide your answer by how many values there are. 

Let's add our values: 
78+79+80+80+89+89+92+93+94+95+95+95 = 1059. 

There are 12 values. So...:
1059/12 = 88.25. It says to round to the nearest tenth. That would be 88.3.