1. a person preparing medicine wants to convert 15% alcohol solution into 32% alcohol
solution. find how much pure alcohol should he mix with 400 ml of 15% alcohol
solution to obtain it.

pls give me an answer to this. i will give 10 points.

100mL

Step-by-step explanation:

A 15% alcohol solution contains 15mL alcohol in 100mL solution

In 400ml there will be 400mL·15/100 = 6,000mL/100 = 60mL alcohol

Let the volume of pure alcohol to be added V.

In the new solution there will be (60 + V)mL  alcohol

And the total volume will be (400 + V)mL

Concentration required 32% = 0.32

Concentration = (60 + V)mL/(400 + V)mL = 0.32

60mL + VmL = 0.32(400 + V)mL

60mL + VmL = 128mL + V·*0.32mL

VmL - V·0.32mL = 128mL - 60mL = 68mL

V(1 - 0.32)mL = 68mL

V·0.68mL = 68mL

VmL = 68mL/0.68 = 100mL ►  alcohol volume to be added

Answer : 100mL

Verification

New solution

There will be  400mL + 100mL = 500mL total volume

There will be 60mL alcohol + 100mL alcohol = 160mL alcohol

The concentration will be   160mL/500mL = 0.32 = 32%



correct answer:

b.(19,-2)

hey! so 1 (25) out of 4 (100) is 25 so your answer is 25%. it's like quarters!