A lab technician mixed two salt solutions, Solution A and Solution B.

Question

A lab technician mixed two salt solutions, Solution A and Solution B. Solution A contained 12% salt, and Solution B contained 4% salt. If the resulting mixture contained 7% salt, how many liters of Solution A were used?

(1) The technician used 20 liters of Solution B.
(2) The resulting mixture was 32 liters.

M47-150

Bunuel · Accepted Answer

GMAT Club Official Solution:

A lab technician mixed two salt solutions, Solution A and Solution B. Solution A contained 12% salt, and Solution B contained 4% salt. If the resulting mixture contained 7% salt, how many liters of Solution A were used?

Let A be the number of liters of Solution A, and let B be the number of liters of Solution B. Since Solution A contained 12% salt, Solution B contained 4% salt, and the resulting mixture contained 7% salt:

0.12A + 0.04B = 0.07(A + B)

12A + 4B = 7A + 7B

5A = 3B

A/B = 3/5

So the ratio of the amount of Solution A to the amount of Solution B is 3 to 5.

(1) The technician used 20 liters of Solution B.

So, B = 20 and thus:

A/20 = 3/5

A = 12

Sufficient.

(2) The resulting mixture was 32 liters.

This gives A + B = 32. Since the total mixture is split in the ratio 3:5, A = 12 and B = 20.

Sufficient.

Answer: D.

ankushsambare · Answer

Let A = liters of Solution A and B = liters of Solution B.
0.12A + 0.04B = 0.07(A + B)
0.12A + 0.04B = 0.07A + 0.07B
0.05A = 0.03B
A/B = 3/5 so A = (3/5)B
(1) B = 20, so A = (3/5) × 20 = 12 → sufficient
(2) A + B = 32, ratio A:B = 3:5 so total 8 parts → each part = 4 → A = 12 → sufficient
Each statement alone is sufficient.
 Answer: D

gargipratapsingh · Answer

Through alligation, Va:Vb=3:5

Statement 1. B=20
3/5=Va/20, Va=60/5, Va= 12 litre
Hence statement 1 is sufficient

Statement 2. Resultant Mixture= 32
which is in the ratio 3:5
so, 3k+5k=8k
8k=32, k= 4
Solution A is 3k, so 3x4 =12 litre
Hence statement 2 is sufficient

Answer will be  D

BongBideshini · Answer

Using alligation 
A × 5 = B × 3 
A : B = 3 : 5 
 \frac{A}{B }=\frac{3}{5}

Statement (1) 
B = 20 liters
A = (3/5) × 20 = 12

SUFFICIENT 
 Statement (2)  
Total mixture = 32 liters

\frac{A}{B} =\frac{3}{5}
=> \frac{A}{A+B} =\frac{3}{5+3}
=>A=\frac{3}{8}*32
=>A=12

SUFFICIENT

ANS (D)

A lab technician mixed two salt solutions, Solution A and Solution B.

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