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Sever21 [200]
3 years ago
8

A scientist wants a 66 ounce saline solution with concentration 12% . She has concentrations of 4% and 15% . How much of each so

lution must she use to get the desired concentration?
Mathematics
1 answer:
Bess [88]3 years ago
6 0
Let x and y represent the measure in ounces of the two given saline solutions.  We are mixing these two together, so x + y = 66 ounces.

The amount of the 4% solution to be used is 0.04x, and that of the 15% solution is 0.15y. 

This results in the equation .04x + 0.15y = 66(0.12).

Multiply both sides by 100 to remove the decimal fractions.  Then

4x + 15y = 66(12).  Now eliminate the variable x by recalling that x + y = 66 ounces, so that x = 66 - y.

Substituting, 4(66 - y) + 15y = 66(12)
Expanding, 264 - 4y + 15 y = 792
combining like terms:    11y = 528

Solving for y:  y = 528/11 = 48.  Then x = 66 - 48 = 18.

Use 48 ounces of the 15% solution and 18 ounces of the 4% solution to obtain 66 ounces of a 12% solution.
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Which set represents a pythagorean triple
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Answer:

30, 40, 50 which is choice C

Step-by-step explanation:

Square the smaller two values (30 and 40)

30^2 = 900

40^2 = 1600

then add those results

900+1600 = 2500

Notice how 50^2 = 2500 as well. This shows us that 30^2 + 40^2 = 50^2 is a true equation. Both sides lead to the same result 2500. Therefore, a triangle with sides 30, 40, 50 is a right triangle. This is based on the 3-4-5 pythagorean triple, just each side has been multiplied by 10.

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Answer:16

Step-by-step explanation:

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Factor 2n(n + 3) - 5(n + 3).
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2n(n + 3) - 5(n + 3) = (2n-5)(n+3)

A. (n + 3) (2n - 5)
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4 years ago
BRAINLIEST FOR WHOEVER ANSWERS FIRST!!!!
Fofino [41]

Answer:

x = 34

Step-by-step explanation:

ΔABD and ΔBCD are both isosceles triangles

In ΔABD

AB =AD, hence ∠ABD = ∠ADB ( base angles are equal )

∠ABD = \frac{180-44}{2} = \frac{136}{2} = 68°

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∠BCD = x = \frac{180-112}{2} = \frac{68}{2} = 34


4 0
3 years ago
A study is conducted to determine if a newly designed text book is more helpful to learning the material than the old edition. T
CaHeK987 [17]

Answer:

We need to conduct a hypothesis in order to check if the mean is higher than 75, the system of hypothesis are :  

Null hypothesis:\mu \leq 75  

Alternative hypothesis:\mu > 75  

A. One-Tailed

z=\frac{82.2-75}{\frac{10.4}{\sqrt{10}}}=2.189  

p_v =P(z>2.189)=0.0143  

If we compare the p value and the significance level given \alpha=0.01 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.

Step-by-step explanation:

Data given and notation  

We have the following data: 84 94 80 88 77 68 90 74 96 71

We can calculate the sample mean with the following formula:

\bar X =\frac{\sum_{i=1}^n X_i}{n}

And replacing we got:

\bar X=82.2 represent the sample mean  

\sigma=10.4 represent the population standard deviation  

n=10 sample size  

\mu_o =75 represent the value that we want to test  

\alpha=0.01 represent the significance level for the hypothesis test.  

z would represent the statistic (variable of interest)  

p_v represent the p value for the test (variable of interest)  

State the null and alternative hypotheses.  

We need to conduct a hypothesis in order to check if the mean is higher than 75, the system of hypothesis are :  

Null hypothesis:\mu \leq 75  

Alternative hypothesis:\mu > 75  

A. One-Tailed

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:  

z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}} (1)  

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".  

Calculate the statistic  

We can replace in formula (1) the info given like this:  

z=\frac{82.2-75}{\frac{10.4}{\sqrt{10}}}=2.189  

P-value  

Since is a ONE-TAILED  test the p value would given by:  

p_v =P(z>2.189)=0.0143  

Conclusion  

If we compare the p value and the significance level given \alpha=0.01 we see that p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis.

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3 years ago
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