Partial fluid changes

[markweatherill]

I've done two partial ATF changes on my car, spaced some weeks apart.

It holds 4.4L of ATF. I drained and replaced around 2.2L each time.

Can someone show me how to work out what proportion of new to old fluid I now have? I know the first change gives me 50% new fluid. What does the second change give me??

[user removed]

4.4/2.2=50% first change

second change, you are changing half of the fluid again, but only half of it is old fluid. so 75%.

regards
mech