### Problem

Given a stream of numbers, print average (or mean) of the stream at every point.### Example

For example, let us consider the stream as 10, 20, 30, 40, 50, 60, …Average of 1 numbers is 10.00 Average of 2 numbers is 15.00 Average of 3 numbers is 20.00 Average of 4 numbers is 25.00 Average of 5 numbers is 30.00 Average of 6 numbers is 35.00 ..................

### Solution

To print mean of a stream, we need to find out how to find average when a new number is being added to the stream. To do this, all we need is count of numbers seen so far in the stream, previous average and new number. Let*n*be the count,

*prev_avg*be the previous average and x be the new number being added. The average after including

*x*number can be written as

*(prev_avg*n + x)/(n+1)*.

float getAvg(float prev_avg, int x, int n) { return (prev_avg*n + x)/(n+1); } // Prints average of a stream of numbers void streamAvg(float arr[], int n) { float avg = 0; for(int i = 0; i < n; i++) { avg = getAvg(avg, arr[i], i); out.println("Average of "+String.valueOf(i+1)+" numbers is "+avg); } return; }

**References**

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