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3 years ago

10

A chemist has 0.2 liters of an acid solution whose acid concentration is 65%. How many liters of pure water should be added to l

ower the concentration to 50%?

1 answer:

lorasvet [3.4K]3 years ago

4 0

Answer:

0.06

Step-by-step explanation:

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Jessica can do 60 jumping jacks in 2 minutes. Dale can do 150 jumping jacksin 5 minutes. Are these rates equivalent?

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Read 2 more answers

20 points! I will mark brainliest

IceJOKER [234]

Answer:

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so AC is the shortest distance.

<h3>step by step explanation</h3>

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to find that we use the distance formula .

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Sydney planted 5/9 of her fall flowers. she had 63 unplanted flowers to start how many flowers does she have left to plant

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Since Sydney has planted 5/9 of her flowers and there were 63 flowers that are left unplanted, the first thing we are going to determine is the number of flowers that were planted. To do this, we just have to do the cross multiplication process.
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3 years ago

A local marketing company wants to estimate the proportion of consumers in the Oconee County area who would react favorably to a

Burka [1]

Answer:

C. n=423

Step-by-step explanation:

1) Notation and important concepts

Margin of error for a proportion is defined as "percentage points your results will differ from the real population value"

Confidence=90%=0.9

$\alpha=1-0.9=0.1$ represent the significance level defined as "a measure of the strength of the evidence that must be present in your sample before you will reject the null hypothesis and conclude that the effect is statistically significant".

$\hat p=0.5$ represent the sample proportion of consumers in the Oconee County area who would react favorably to a marketing campaig. For this case since we don't have enough info we use the value of 0.5 since is equiprobable the event analyzed.

$z_{\alpha/2}$ represent a quantile of the normal standard distribution that accumulates ${\alpha/2}$ on each tail of the distribution.

2) Formulas and solution for the problem

For this case the margin of error for a proportion is given by this formula

$ME=z_{\alpha/2}\sqrt{\frac{\hat p(1-\hat p)}{n}}$ (1)

For this case the confidence level is 90% or 0.9 so then the significance would be

$\alpha=1-0.9=0.1$ and $\alpha/2=0.05$

With $\alpha/2=0.05$ , we can find the value for $z_{\alpha/2}$ using the normal standard distribution table or excel.

The calculated value is $z_{\alpha/2}=1.644854$

Now from equation (1) we need to solve for n in order to answer the question.

$\frac{ME}{z_{\alpha/2}}=\sqrt{\frac{\hat p(1-\hat p)}{n}}$

Squaring both sides:

$(\frac{ME}{z_{\alpha/2}})^2=\frac{\hat p(1-\hat p)}{n}$

And solving for n we got:

$n=\frac{\hat p(1-\hat p)}{(\frac{ME}{z_{\alpha/2}})^2}$

Now we can replpace the values

$n=\frac{0.5(1-0.5)}{(\frac{0.04}{1.644854})^2}=422.739$

And rounded up to the nearest integer we got:

n=423

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3 years ago

What is the answer to K/-3=9

Kay [80]

K = -27 I think that’s right

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4 years ago