A tabulator while calculating the average marks of $100\text{ students}$ in an examination, by mistake enters $6.8$, instead of $8.6$ and obtains the average as $5.8$. Then the actual average marks of those students is:

Given data:
* Total number of students ($n$) = $100$
* Incorrect average = $5.8$
* Incorrect value recorded = $6.8$
* Correct value to be recorded = $8.6$

First, find the incorrect sum of marks:

$$\text{Incorrect Sum}=100\times 5.8=580$$

Now, compute the correct sum of marks by removing the wrong entry and adding the correct entry:

$$\text{Correct Sum}=\text{Incorrect Sum}-\text{Incorrect Value}+\text{Correct Value}$$

$$\text{Correct Sum}=580-6.8+8.6=580+1.8=581.8$$

Finally, calculate the actual (correct) average:

$$\text{Actual Average}=\frac{\text{Correct Sum}}{n}=\frac{581.8}{100}=5.818$$