Correct Answer: 6 ml
Explanation:
Step 1: Understand the given
Initial lotion volume = 9 ml
Alcohol concentration = 50% ⇒ Alcohol = 0.5 × 9 = 4.5 ml
Step 2: Let x ml of water be added
New total volume = 9 + x ml
Alcohol remains unchanged = 4.5 ml
Step 3: Set up the equation
New alcohol percentage = 30%
So, 4.5 / (9 + x) = 0.30
Step 4: Solve the equation
4.5 = 0.30 × (9 + x)
4.5 = 2.7 + 0.30x
4.5 - 2.7 = 0.30x
1.8 = 0.30x
x = 1.8 / 0.30 = 6
Answer: 6 ml of water should be added.
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