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Bezzdna [24]
3 years ago
6

A chemist has two acid solutions in stock: one is a 50% solution, and the other is a 80% solution. How much of each solution sho

uld be mixed to obtain 100 milliliters of a 68% solution?
Mathematics
1 answer:
arsen [322]3 years ago
8 0
Easy way, visual

                    50---68---80%
Difference        18    12
Invert order to give ratio of 50% and 80%
Ratio                12    18 = 2:3

So by simple proportion:
volume of 50% needed = 100*2/(2+3)=40 mL
volume of 80% needed = 100*3/(2+3)=60 mL

Algebra way
Let x=volume of 50% needed.
Then
0.50*x+0.80*(100-x) = 0.68(100)
Expand and solve for x
0.5x+80-0.8x = 68
0.8x-0.5x = 80-68
0.3x = 12
x=12/0.3 = 40 mL (volume of 50%)
100-x=100-40=60 mL (volume of 80%)

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1.5 hrs

Step-by-step explanation:

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Grace is looking at a report of her monthly cell-phone usage for the last year to determine if she needs to upgrade her plan. Th
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Answer:

s ≈ 105

Step-by-step explanation:

<u>Given:</u>

  • The data set: 700, 735, 680, 890, 755, 740, 670, 785, 805, 1050, 820, 750

<u>To find:</u>

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<u>Steps:</u>

To find the standard deviation, first write the computational formula for the standard deviation of the sample.

{s}= \sqrt{\frac{{\sum}{x^2} - \frac{({\sum}{x})^2}{n}}{n - 1}}

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6 0
1 year ago
The measure of ∠AKG is 133°.
denis23 [38]
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133° = mes ∠ AKD + 87°

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7 0
3 years ago
Where e is enclosed by the planes z = 0 and z = x + y + 9 and by the cylinders x2 + y2 = 4 and x2 + y2 = 16?
katrin [286]
Best to use cylindrical coordinates. The volume (assuming that's what you're supposed to find) of the region is given by the triple integral

\displaystyle\iiint_E\mathrm dV=\int_{\theta=0}^{\theta=2\pi}\int_{r=2}^{r=4}\int_{z=0}^{z=r(\cos\theta+\sin\theta)+9}r\,\mathrm dz\,\mathrm dr\,\mathrm d\theta
=\displaystyle\int_{\theta=0}^{\theta=2\pi}\int_{r=2}^{r=4}(r^2(\cos\theta+\sin\theta)+9r)\,\mathrm dr\,\mathrm d\theta
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4 0
3 years ago
If 1 gram = 100 centigrams and 1 centigram = 10 milligrams, how many
Alja [10]

Answer:

1,420 milligrams

Step-by-step explanation:

We know there are 100 centigrams in 1 gram, and there are 10 milligrams in a centigrams. That would mean there are 1,000 milligrams in 1 gram (100 * 10 = 1000).

As a result, all you need to do is multiply 1.42 by 1000 to get the amount of milligrams.

1.42 * 1000

Alternatively, to make 1.42 a whole number first, multiply by 100, then add a zero. (That's the other 10!)

(1.42 * 100) * 10

142 * 10

There are 1,420 milligrams in 1.42 grams.

3 0
2 years ago
Read 2 more answers
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