Answer: 0.111111111111111
Step-by-step explanation:
Let n be the total number of puffs. Now we can write:

Adding the fractional value of n, we get:

Simplifying and rearranging gives us:

Therefore we can simplify to get:

and finally

The fraction of the puff that are tuna is found from:
First find the mean (sum divided by number of values)
4+5+8+10+15=42
42/5=8.4
Then find the difference between each of the numbers and the mean.
4.4, 3.4, 0.4, 1.6, 6.6
Then find the mean of those values.
4.4+3.4+0.4+1.6+6.6=16.4
16.4/5=3.28
Final answer: 3.28
All the sides add like a rectangle with two sides measuring 4 and two measuring 2 so you would add 4+4+2+2=12