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

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Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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Updated on: 27 Jun 2015, 06:22
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Question Stats:

73% (02:19) correct 27% (02:44) wrong based on 433 sessions

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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

Originally posted by cloaked_vessel on 04 Apr 2005, 11:04.
Last edited by Bunuel on 27 Jun 2015, 06:22, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
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Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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30 Jun 2015, 03:22
8
4
arshu27 wrote:
cloaked_vessel wrote:
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

"Bunuel,

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

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: http://www.veritasprep.com/blog/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.

Another approach would be just to plug in the answers and work backwards.

Hope it helps.
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29 Jul 2009, 09:21
2
2
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.
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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04 Apr 2005, 13:10
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3*0,05+0,2x=0,15(x+3) => x=6 => D!
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A chemist has 3 liters of a bleaching chemical, Minum, which is compos  [#permalink]

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18 Oct 2015, 08:36
1
(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.

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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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16 Aug 2017, 09:45
1
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!
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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04 Apr 2005, 12:55
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
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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05 Apr 2005, 08:12
3
cloaked_vessel wrote:
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

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
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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29 Jun 2015, 14:11
cloaked_vessel wrote:
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

"Bunuel,

can you please explain the solution stepwise as i have no idea as to how to start this sort of mixture questions. Thanks!
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Re: A chemist has 3 liters of a bleaching chemical, Minum, which is compos  [#permalink]

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18 Oct 2015, 08:30
shyind wrote:
A chemist has 3 liters of a bleaching chemical, Minum, which is composed of 5 percent hydrogen peroxide. A different type of bleaching chemical, Maxim, which is composed of 20 percent hydrogen peroxide, will be mixed with three liters of Minum. How many liters of maxim should be added to the three liters of Minum so that the resulting mixture is 15 percent Hydrogen peroxide.

A. 3

B. 3.75

C. 4.5

D. 6

E. 9

x=the number of liters of Maxim

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

Ans: D
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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18 Oct 2015, 12:24
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
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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04 Apr 2016, 08:41
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.
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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26 Jul 2016, 21:00
let x=liters of Maxim to be added
3*.05+x*.2=.15(3+x)
x=6 quarts
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Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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16 Aug 2017, 18:22
cloaked_vessel wrote:
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

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

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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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21 Aug 2017, 08:34
cloaked_vessel wrote:
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

Using allegation :
Let x be the quantity of Maxim added
3/x=(20-15)/(15-5)
x=6
Ans. D
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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02 Nov 2017, 16:07
how do we backsolve this by using answer options?
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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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06 Nov 2017, 18:07
cloaked_vessel wrote:
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

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

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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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14 Nov 2017, 03:12
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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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog  [#permalink]

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Re: Three quarts of a bleaching chemical, Minum, contains 5 percent hydrog   [#permalink] 09 Aug 2019, 01:02
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