Jing the scientist has one solution that is 30% acid and another solution that is 18% acid. Solution that she should use to get 300 L of a solution that is 21% acid is 75L.
Acid is a substance whose pH is less than 7.
Given,
30% of a solution with 18% of another solution makes 300L of another solution with 21% acid.
Let x be the quantity of solution one in mixture.
Hence, another solution would be (300-x) L
According to given question,
30% of x + 18% of (300-x) = 21% of 300
i.e. 30x/100 + 18(300-x)/100= 21 × 300/100
=> 30x - 18x = 6300 - 5400
=> 12x = 900
=> x = 75L
Hence, 75L of each solution is required to get 300 L of a solution that is 21% acid.
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