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A chemical supply company has 60 liters of a 40% HNO3 solution.

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A chemical supply company has 60 liters of a 40% HNO3 solution.  [#permalink]

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New post 01 Oct 2016, 11:07
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A chemical supply company has 60 liters of a 40% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?

A) 12
B) 15
C) 20
D) 24
E) 30
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Re: A chemical supply company has 60 liters of a 40% HNO3 solution.  [#permalink]

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New post 02 Oct 2016, 01:31
lalania1 wrote:
A chemical supply company has 60 liters of a 40% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?

A) 12
B) 15
C) 20
D) 24
E) 30


Another simple one.

60 liters of a 40% HNO3 solution means HNO3 = 24 liters in 60 liters of the solution.

Now, let x be the pure HNO3 added.

As per question,

24 + x = 50% of (60 + x)

or x =12. Hence, A
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A chemical supply company has 60 liters of a 40% HNO3 solution.  [#permalink]

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New post 02 Oct 2016, 16:27
lalania1 wrote:
A chemical supply company has 60 liters of a 40% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?

A) 12
B) 15
C) 20
D) 24
E) 30


Use weighted Avg:

\(\frac{W1}{W2}=\frac{(A2-Avg)}{(Avg-A1)}\)
Here W1 = 60; W2 is what we need to find.
Avg = 50%; A1 = 40%; A2 = 100%
\(\frac{60}{W2}=\frac{(100-50)}{(50-40)}=\frac{5}{1}\)
W2 = 12
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Re: A chemical supply company has 60 liters of a 40% HNO3 solution.  [#permalink]

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New post 05 Apr 2018, 17:13
lalania1 wrote:
A chemical supply company has 60 liters of a 40% HNO3 solution. How many liters of pure undiluted HNO3 must the chemists add so that the resultant solution is a 50% solution?

A) 12
B) 15
C) 20
D) 24
E) 30


We can lert n = the amount of pure undiluted HNO3 to be added and create the equation:

(0.4 x 60 + n)/(60 + n) = 1/2

2(24 + n) = 60 + n

48 + 2n = 60 + n

n = 12

Answer: A
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Re: A chemical supply company has 60 liters of a 40% HNO3 solution. &nbs [#permalink] 05 Apr 2018, 17:13
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