The amount of the hair color needed ( in ml ) to the amount of developer used (75 ml) for this case is 50 ml
Two ratios form a proportion if simplified form of both the ratios comes out as same ratio.
For this case, we're specified that:
Hair color : Developer is proportional to 1 : 1.5
Now, the developer used is 75 ml, let the hair color to be used is x ml, such that its proportional to 1 : 1.5, then:
[tex]x:75 :: 1:15\\\\\dfrac{x}{75} = \dfrac{1}{1.5}\\\\\\\text{Multiplying 75 on both the sides}\\\\x = \dfrac{75}{1.5} = \dfrac{750}{15} = 50 \: \rm ml[/tex]
(in the second step we used fractions to get the simple form of ratio and because of that, there is equality sign in both ratio's simplified form).
Thus, the amount of the hair color needed ( in ml ) to the amount of developer used (75 ml) for this case is 50 ml
Learn more about ratio and proportion here:
https://brainly.com/question/13513438
