Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog

Question

Three quarts of a bleaching chemical, Minum, contains 5 percent hydrogen peroxide and water. A different type of bleaching chemical, Maxim, which contains 20 percent hydrogen peroxide, will be mixed with the three quarts of Minum. How much of type Maxim should be added to the three quarts of Minum so that the resulting mixture contains 15 percent hydrogen peroxide?

A) 3 quarts

B) 3.75 quarts

C) 4.5 quarts

D) 6 quarts

E) 9 quarts

A. 3 quarts
B. 3.75 quarts
C. 4.5 quarts
D. 6 quarts
E. 9 quarts

Bunuel · Accepted Answer

Approach #1: Minum contains 5 percent hydrogen peroxide. Maxim contains 20 percent hydrogen peroxide. Minum:Maxim = (20 - 15):(15 - 5) = 1:2. (Check for more here: https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2011/04 ... -mixtures/) So, for the final concentration to be 15% for every par of Minum we should take 2 parts of Maxim. Since, we are mixing 3 parts of Minum, we should take 3*2 = 6 parts of Maxim. Approach #2: Equate hydrogen peroxide: 5% of 3 parts + 20% of x parts = 15% of total, so 15% of 3 + x parts: 0.05*3 + 0.2*x = 0.15(3 + x) x = 6. Answer: D. Another approach would be just to plug in the answers and work backwards. Hope it helps.

thearch · Answer

say one quart is 100/3
you have 0.05*100=5
then backsolve
start from C -> 4.5*100/3=150
150*0.2=30
in the new mixture there are 35/250
we needed 37.5 (more)
now D 
6*100/3=200
200*0.2=40
  45/300  
  perfect

christoph · Answer

3*0,05+0,2x=0,15(x+3) => x=6 => D!

ssap · Answer

Ans id 'D'
5% HydPer&Water (HPW) of 3 quart of Minum= .15 q
20% of HPW of x q of Maxim = .2x
Total = .15 + .2x = .15 (3+x)
Solving , x=6 quart

sudiptak · Answer

The answer is 6.
let 'x' be the qty of maxim which has to be mixed with minum.
so, the total qty of the mixture=(x+3).
Since the mixture has 15% of hydrogen peroxide
we can have the eqn as
(5%*3)+(20%*x)=15%*(x+3)
solving this we get x=6.

hence D.

arshu27 · Answer

"Bunuel,

can you please explain the solution stepwise as i have no idea as to how to start this sort of mixture questions. Thanks!

camlan1990 · Answer

x=the number of liters of Maxim

15(x+3) = 5*3 + 20x
=> x = 6

Ans: D

paulaalv11 · Answer

(1) The variables in the problem
 m =  # liters of minum;  cm = concentration (%) of minum
 M =  # liters of Maxim;  cM = concentration (%) of Maxim
 T =  # liters in total after mixing both minum and Maxim;  cT = concentration (%) of the mixture

(2) What we know from the stem
From the stem, we know that  m=3, rm = 5, rM=20 .  M  is unknown.
 T = m + M = 3 + M 
What we want to know:  M

(3)From all of thi above, we have that

\frac{m * cm + M * cM}{T} = cT

(4) Plugging in the values from (2):

\frac{3 * 5 + M * 20}{(3 + M)} = 15

If we solve for  M  we get  M=6 , so is the correct answer.

Hope this helps! Please, kudos!!!

OptimusPrepJanielle · Answer

We just need to equate the hydrogen peroxide here

5% of 3 + 20% of x = 15% of (x+3)
0.05*3 + 0.2*x = 0.15(3 + x)
0.15 + 0.2x = 0.45 +0.15x
0.05x = 0.3

x = 6 Option D

psahoo · Answer

Minum contains 5% hydrogen peroxide, Maxim contains 20%. 
Mixture contains 15%.

Applying ratio and mixture rule Minum and Maxim should be mixed in ratio (20-15):(15-5) or 5:10 or 1:2.

Minum is of 3 quarts. So Maxim should be of 6 quarts.

gracie · Answer

let x=liters of Maxim to be added
3*.05+x*.2=.15(3+x)
x=6 quarts

rever08 · Answer

Minum contains 5 percent hydrogen peroxide.
Maxim contains 20 percent hydrogen peroxide.

Minum:Maxim = (20 - 15):(15 - 5) = 1:2. (Using Alligation)

So, since Minum is 3 quarts, Maxim will be 6 quarts!

generis · Answer

Simplifying the arithmetic a bit by changing decimal percent concentrations to integers . . .

Let x = amount of Maxim to be added

5(3) + 20(x) = 15(3 + x)
15 + 20x = 45 + 15x
5x = 30
x = 6

Answer D

Dkingdom · Answer

Using allegation : 
Let x be the quantity of Maxim added 
3/x=(20-15)/(15-5)
x=6 
Ans. D

santro789 · Answer

how do we backsolve this by using answer options?

ScottTargetTestPrep · Answer

We can let the number of quarts of Maxim = y and create the following equations:

0.05(3) + 0.2y = 0.15(3 + y)

5(3) + 20y = 15(3 + y)

15 + 20y = 45 + 15y

5y = 30

y = 6

Answer: D

gps5441 · Answer

Weighted avg method.
Formula
w1/w2=(a2-avg)/avg-a1)
a2=20
Avg=15
a1=5
plug in
w1/w2=(20-15)/(10-5)=1/2
w1=3
3/w2=1/2 0r w2=6.

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Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog

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