You need a 30% alcohol solution. on hand, you have a 90 ml of a 45% alcohol mixture. how much pure water will you need to add to obtain the desired solution?
you will need
ml of pure water
to obtain
ml of the desired 30% solution.

45ml of pure water to obtain 135ml of the desired 30% solution

Step-by-step explanation:

45% of 90 = 40.5

So, 40.5ml of alcohol in 90ml

We want 30% and therefore need a ratio of 3:7

40.5÷3=13.5

so one part of our ratio is 13.5

we then times this by 7

13.5 x 7 = 94.5

so, 94.5ml of water

to work out how much we already have, we should do 90ml- 40.5ml = 49.5ml

and then 94.5- 49.5 = 45ml

We need 45ml of water and the total mo of the desired solution will be 90+45=135ml

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.