Is it possible to calculate the regular average of a sequence of numbers when i dont know everything of the sequence, but just everytime i get a new number i know the total count of numbers and the average for the numbers $-1$.

for example: $2,3,10$ the average is of course: $5$

but in the last step to calculate i only have access to the previous average of $2$ and $3:2.5$ the next number: $10$ and the count of numbers: $3$

if this is possible, how?

for example: $2,3,10$ the average is of course: $5$

but in the last step to calculate i only have access to the previous average of $2$ and $3:2.5$ the next number: $10$ and the count of numbers: $3$

if this is possible, how?