How to incrementally take average in Oracle SQL Or Python

I am bit stuck with this not getting how do i proceed further

Assume I have below data in table

Note : All the below column fields [NAME , AGE , COURSE , MARKS] are set to VARCHAR2(50 CHAR)

NAME | AGE | COURSE | MARKS 
A1   | ABC | MCA    | 5 
B1   | XYZ | MBA    | 10
C1   | PQR | MMS    | 14
D1   | YST | CAT    | 18

Using below query I am able to get incremental sum , but not able to apply logic how to get incremental average

My Query :

select c1.* , SUM(MARKS) Over (Order by c1.NAME) AS CUM_COUNT from EMP c1 order by c1.NAME ASC;

Expected output :

NAME | AGE | COURSE | MARKS | CUM_COUNT | AVGS_CNT      |
A1   | ABC | MCA    | 5     | 5   | 5/1  = 5      |
B1   | XYZ | MBA    | 10    | 15  | 15/2 = 7.5    |
C1   | PQR | MMS    | 14    | 29  | 29/3 = 9.6    |
D1   | YST | CAT    | 18    | 47  | 47/4 = 11.75  |

Solution in oracle OR python appreciated

Note : I have date in Oracle

The reason behind asking this question as it was asked to me in interview

Answer

To complement @mathguy’s answer, here the full query you need:

select
  e.*,
  sum(marks) over(order by name) as cum_count,
  1.0 * sum(marks) over(order by name) / count(*) over(order by name) as avgs_cnt
from emp e

Result:

 NAME  AGE  COURSE  MARKS  CUM_COUNT  AVGS_CNT         
 ----- ---- ------- ------ ---------- ---------------- 
 A1    ABC  MCA     5      5          5                
 B1    XYZ  MBA     10     15         7.5              
 C1    PQR  MMS     14     29         9.66666666666667 
 D1    YST  CAT     18     47         11.75            

It uses windows functions by qualifying SUM() and COUNT(*) with OVER(ORDER BY NAME).

See running example at db<>fiddle.