You need 70% alcohol. In what proportion should 95%, 60%, and 50% alcohol be mixed to prepare a solvent of the desired concentration?             

(3 marks)

Using the alligation method, calculate the proportions for two mixture.

First one using 95% and 60%, second one using 95% and 50%.

Mix A:

10 parts 95% + 25 parts 60% = 35 parts 70%

=

2 part 95% + 5 parts 60% = 7 parts 70%

Mix B:

20 parts 95% + 25 parts 50% = 45 parts 70%

=

4 parts 95% + 5 parts 50% = 9 parts 70%

Mix A + Mix B:

2 parts 95% + 4 parts 95% + 5 parts 60% + 5 parts 50% = 16 parts 70%

=

6 parts 95% + 5 parts 60% + 5 parts 50% = 16 parts 70%