Solution: (1) The original plan was to produce an average of 20,000 per day/10 = 2,000 (I);

(2) Suppose the company originally planned to arrange n workers, but one worker can produce (2000/n) a day (top/person/day); After improving the efficiency, each person can produce (2000/n)( 1+0.25)=(2500/n) (per person per day); 50 workers have been added, so it can produce:

(2500/n)(n+50)=2500(n+50)/n (top/day); Therefore, there is an equation:

(20000-2×2000)÷[2500(n+50)/n]=6

That is,16000n =15000 (n+50).

1000n=75000

∴n=75000/ 1000=75

That is, 75 workers were originally planned.