Question

The quantity of water that should be added to reduce 9 ml lotion containing 50% alcohol to a lotion containing 30% alcohol is :

• A. 3 ml
• B. 4 ml
• C. 5 ml
• D. 6 ml

Answer 1

The correct option is D 6 ml

Alcohol in 9 ml lotion = $(\frac{50}{100}\times 9)=4.5ml$

Water in it = $9-4.5=4.5ml$

Let x ml of water be added to it. Then,

$\frac{4.5}{9+x}=\frac{30}{100}=\frac{3}{10}$

$3(9+x)=45$

$3x=18$

$x=6$

Hence, option D is correct.