Answer:
10
Step-by-step explanation:
the sum of 8,5,15,12,10 is 50 and there are 5 numbers so 50 divided by 5 is 10 and it's mean is also 10
hope this helps !
Any other irrational number. 0.4 is rational (ie., it can be written as a fraction), but rational+irrational is always irrational.
So examples would be π or √2. If you add those, the result is irrational.