Any Maths whizzes about to help me calculate alcohol content?

[BigGillsBigMac]

I have a bottle of 400ml hand sanitiser at 45% alcohol.

I have 95% methylated surgical spirit to add to bring it up to a safe pointi would like 70% alcohol in my hand sanitiser.

How much surgical spirit do I need to add?

400mL

I have to add 400ml ss to 400ml hand sanitiser, really?

400mL x 0.95 = 380mL alcohol
400mL x 0.45 = 180mL alcohol.

total 560 mL alcohol out of total 800mL liquid = 800mL.

That's assuming you can actually just add that much liquid and not have it turn into a mess. There probably wouldn't be enough gel to make it the right consistency. Guess it could be a spray though.

sorry I meant 560 out of 800ml = 70%

Thankyou so much. Yes it probably will be very liquid but better than nothing!