I need help with the following calculation.

I have 1 million customers in category A out of 8 million total customerd who 15% of them receive a questionnaire and 5 % respond back. Their score takes the overall satisfaction score for all customets combined by 0.8 to 30.4. What I need to work out is if I can have 200000 more customers in the same category A to estimate how much the scores would improve