How many kilograms of a 15% salt solution must be added to 5 kilograms

Question

How many kilograms of a 15% salt solution must be added to 5 kilograms of a solution that is 8% salt so that the resulting solution is 10% salt?

A. 1
B. 1.5
C. 2
D. 2.5
E. 3

CrackverbalGMAT · Answer

Average Concentration = (C1Q1 + C2Q2) / (Q1 + Q2)

Let the quantity be x.

10 = (8 * 5 + 15x) / (5 + x)

50 + 10x = 40 + 15x

5x = 10

x = 2

Option C

Arun Kumar

imeanup · Answer

Using allegation and mixture

Bunuel · Answer

Veritas Prep Official Explanation

Create a starting equation that accounts for the current conditions: (.4 Kilograms Salt)/(5 Kilograms Total) = 8%. Since you are now adding 15% salt solution instead of pure salt, you must put all of what you add in the denominator but only the salt portion in the numerator: (.4 + .15x)/(5 + x) = 1/10. Cross-multiply to get 4 + 1.5x = 5 + x, so .5x = 1 and x = 2.

dave13 · Answer

meanup  why are you multiplying by 1 ?

imeanup · Answer

Given, 5 kilograms of a solution that is 8% salt. Therefore we are substituting the value 5 kg for the 8% solution here.  \frac{5}{5}=1  We are now multiplying 1 with the second solution i.e. 15% salt first solution.

erv20 · Answer

can you please explain what you mean in this picture?

imeanup · Answer

Here is a better explanation for the above question. Let me know if you need any clarification.

KIP22 · Answer

Let  y  be the solution to be added to the 5kg that is 8% salt.

then :
8%(5kg)+15%( y ) = 10%(5kg+ y )

==>0.4kg+0.15 y =0.1(5kg+ y )

0.4kg+0.15 y =0.5kg+0.1 y

0.05 y =0.1kg.

==> y =(0.1kg/0.05)=2kg

Ans.C

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

How many kilograms of a 15% salt solution must be added to 5 kilograms

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

How many kilograms of a 15% salt solution must be added to 5 kilograms

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards