If Adrian mixes 15 liters of saline solution A with 5 liters of a 40%

Question

If Adrian mixes 15 liters of saline solution A with 5 liters of a 40% saline solution to get a 25% saline solution, what percent saline is solution A ?

a. 5
b. 10
c. 15
d. 20
e. 25

Leo8 · Answer

\frac{x}{100} * 15 +  \frac{40}{100} * 5 =  \frac{25}{100}  * 20

\frac{x}{100}  * 15 + 2 = 5

\frac{x}{100}  =  \frac{3}{15}

x = 20 %

generis · Answer

Let x/100 = unknown percent saline in solution A
% = percent saline in each solution

(% A)(Vol A) + (% B)(Vol B) = (% A+B)(Vol A+B)

\frac{x}{100}(15) + .40(5) = .25(15 + 5)

\frac{15}{100}x + 2 = 5

\frac{15}{100}x= 3

x = (3 * \frac{100}{15}) = 20

Answer D

EgmatQuantExpert · Answer

Ratio in which Solution A and Other solution was mixed = 15: 5 = 3: 1

Saline Concentration of Solution A = x

Saline Concentration of Other Solution = 40%

Overall Concentration = 25%

Using Alligation we can write -

(40-25): ( 25 - x) = 3: 1

15 = 75 - 3x

3x = 60

x = 20%

Correct Answer is    Option D   .

Regards,
Saquib
e-GMAT
Quant Expert

gracie · Answer

let x=saline % of A
15*x+5*.4=20*.25
x=1/5=20%
D

ScottTargetTestPrep · Answer

Let solution A be an x% saline solution; we can create the equation:

15(x/100) + 5(0.4) = 0.25(15 + 5)

15x/100 + 2 = 5

15x/100 = 3

15x = 300

x = 20

Answer: D

pearljiandani · Answer

VeritasKarishma 
If I solve this with your method, I'm not getting the correct answer -

w1/w2 = a2 - Avg / Avg - a1

15/5 = 40-25 / 25-x

3 = 20/25-x

75 - 3x = 20

x = 55/3 which is 18 point something but not 20. Can you please explain where I'm going wrong?

KarishmaB · Answer

Calculation error.

40 - 25 = 15
Correct it to get x = 20

CrackverbalGMAT · Answer

Let A be a y% saline solution.
Thus 15(y/100) + 5(0.4) = 0.25(15+5)
=>15y/100 = 3
=> y =20  (D)

Hope this helps. Keep working  :)

kop18 · Answer

I would use the mixture/allegation concept here.

20  ---------40 (Already given)
 -----25-------(Avg given) 
 15----------5 (both nos given)

The subtraction in mixture/allegation should always subtract the higher value from the smaller value to give the resultant. We must get a positive ratio down because the items in the third line represent the actual weights. So we need to ensure that we get a positive value in the 3rd line. The 1st line must always be populated by "per cents" "per kg" value etc.

Hence, 25-5=20.

youcouldsailaway · Answer

We can solve this using the mixture table. Since we know the final solution contains 5 lts of saline (25% of 20 lts), we can figure out the absolute value of saline in soln. B and then the remainder saline, would be coming from sol. A.

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If Adrian mixes 15 liters of saline solution A with 5 liters of a 40%

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If Adrian mixes 15 liters of saline solution A with 5 liters of a 40%

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