1000 ml of 75% alcohol is used for skin disinfection. There are 95% and 40% alcohol at present. How to prepare 75% alcohol with the above two concentrations What is the detailed algorithm

1000 ml of 75% alcohol is used for skin disinfection. There are 95% and 40% alcohol at present. How to prepare 75% alcohol with the above two concentrations What is the detailed algorithm

The volume ratio of 95% and 40% alcohol is (75-40) / (95-75) = 7 / 4
It needs 95% alcohol, 1000 × 7 / 11 = 636.4ml
Need 40% alcohol 1000 × 4 / 11 = 363.6ml
Mix 95% and 40% alcohol by volume

There are two kinds of alcohol with 75% and 45% concentration. How many grams should be taken from each of these two kinds of alcohol if 300 grams of alcohol with 65% alcohol are prepared

Let 75 be x g and 45 be (300-x) g
Equation:
〔75X＋45（300－X）〕／300＝65.
We can calculate 75.45.65% of the total
X＝200
100 grams of 45

How to prepare 1500 g 75% alcohol with 60% alcohol and 90% alcohol

If 60% alcohol x g is needed, 90% alcohol 1500-x G is needed
X＊60%＋（1500－X）＊90%＝1500＊75%
X = 750 g
That is, 750 g of 60% alcohol and 1500-750 = 750 g of 90% alcohol can be mixed