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Gnom [1K]
3 years ago
7

WILL GIVE BRAINLIEST!!!! Write the following as an EXPRESSION: How much water do I need to add to l liters of pure alcohol to ob

tain a solution of 45% alcohol?
Mathematics
1 answer:
nydimaria [60]3 years ago
5 0

Answer:

If you add 690 ml of water you will obtain 1.690 liter of 70% alcohol. Of course if you halve the amounts, e.g. 0.5 liter 75% alcohol and 345 ml of water, you will also obtain 45% alcohol solution.

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Help Please 25 points for real answers
trasher [3.6K]
1. B
 
2. D

3. C= πD
 a) 204π or  641 cm 
A= π r²
 b) π (102)²
10404π squared cm or 32669 squared cm

4. C

5. D
7 0
3 years ago
A certain circle can be represented by the following equation. x^2+y^2+18x+14y+105=0 What is the center of the circle? What is t
Gre4nikov [31]

Answer:

See below.

Step-by-step explanation:

Recall the equation for a circle:

(x-h)^2+(y-k)^2=r^2, where (h,k) is the center and r is the radius.

We need to turn the given equation into the above format. We do this by completing the square.

First, group them:

(x^2+18x)+(y^2+14y)=-105

For the first section, complete the square for x^2+18x:

x^2+18x+81-81

(x+9)^2-81

Do the same for the second:

y^2+14y

y^2+14y+49-49

(y+7)^2-49

All together:

((x+9)^2-81)+((y+7)^2-49)=-105

(x+9)^2+(y+7)^2-130=-105

(x+9)^2+(y+7)^2=25

The center is (-9,-7).

The radius is \sqrt{25}=5

5 0
3 years ago
Mr. Dewalt suggested contacting a travel agent to see whether they could get a lower price. The agent found a price that was 30%
Dennis_Churaev [7]
First you have to know, that the price the agent found is 70% of  $2075
 (100%-30%=70%)
70%=0,7
$2075 * 0,7 = $1452,5
So 70% 0f $2075 is 1452,5

The price the agant found is $1452,5.
5 0
3 years ago
The mean weight of an adult is 69 kilograms with a variance of 121. If 31 adults are randomly selected, what is the probability
amid [387]

Answer:

0.2236 = 22.36% probability that the sample mean would be greater than 70.5 kilograms.

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Also, important to remember that the standard deviation is the square root of the variance.

Normal probability distribution:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem:

The Central Limit Theorem estabilishes that, for a random variable X, with mean \mu and standard deviation \sigma, the sample means with size n of at least 30 can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}

In this problem, we have that:

\mu = 69, \sigma = \sqrt{121} = 11, n = 31, s = \frac{11}{\sqrt{31}} = 1.97565

What is the probability that the sample mean would be greater than 70.5 kilograms?

This is 1 subtracted by the pvalue of Z when X = 70.5. So

Z = \frac{X - \mu}{\sigma}

By the Central limit theorem

Z = \frac{X - \mu}{s}

Z = \frac{70.5 - 69}{1.97565}

Z = 0.76

Z = 0.76 has a pvalue of 0.7764

1 - 0.7764 = 0.2236

0.2236 = 22.36% probability that the sample mean would be greater than 70.5 kilograms.

8 0
3 years ago
Thirty-one books are arranged from left to right in order of increasing prices. The price of each book differs by $2 from that o
user100 [1]
The answer for this problem is 2 since it is not specified whether it is adjacent to the right or adjacent to the left.
If it is adjacent to the right, the answer is:

p (k) = 2 * p(1) + 2 * k

If the is adjacent to the left, the answer is:

P (k) = 2 *p(1) +2 * (k-2)
6 0
3 years ago
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