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BigorU [14]
3 years ago
14

A chemist is mixing a 30% salt solution with a 20% salt solution to make 35 L of a new solution that will contain 25% salt. How

much of the 30% solution should the chemist use?
Mathematics
1 answer:
Grace [21]3 years ago
4 0

Answer:

17.5 L

Step-by-step explanation:

x L  of  30% solution , has 0.30x salt

35 L of 25 % solution, has (0.25*35) salt

(35 - x)L  20% solution, has 0.20*(35 - x) salt

Mass of salt before mixing = mass of salt after mixing

0.3x + 0.2(35 - x) = 0.25* 35

0.3 x + 7 - 0.2x = 8.75

0.1x = 8.75 -7

0.1x = 1.75

x = 17.5 L

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If KL = LM and KJ = JM, find m ∠KJL<br><br> please, i really need your help!
umka2103 [35]
The triangles are congruent by SAS, so the two angles with 7x and 3x+16 are equal. So

7x=3x+16
4x=16
x=4

So KJL=7(4)=28.
3 0
3 years ago
Scores of an IQ test have a​ bell-shaped distribution with a mean of 100 and a standard deviation of 13. Use the empirical rule
Yuri [45]

Answer:

(a) 68% of people has an IQ score between 87 and 113​.

(b) 5% of people has an IQ score less than 74 or greater than 126.

(c) 0.15% of people has an IQ score greater than 139​.

Step-by-step explanation:

Given information:Scores of an IQ test have a​ bell-shaped distribution,

mean = 100

standard deviation = 13

According to the empirical rule

68% data lies between \overline{x}-\sigma and \overline{x}+\sigma.

95% data lies between \overline{x}-2\sigma and \overline{x}+2\sigma.

99.7% data lies between \overline{x}-3\sigma and \overline{x}+3\sigma.

(a)

\overline{x}-\sigma=100-13=87

\overline{x}+\sigma=100+13=113

[\overline{x}-\sigma,\overline{x}+\sigma]=[87,113]

Using empirical rule we can say that 68% of people has an IQ score between 87 and 113​.

(b)

\overline{x}-2\sigma=100-2(13)=74

\overline{x}+2\sigma=100+2(13)=126

[\overline{x}-2\sigma,\overline{x}+2\sigma]=[74,126]

Using empirical rule we can say that 95% of people has an IQ score between 74 and 126​.

The percentage of people has an IQ score less than 74 or greater than 126 is

P = 1- percent of people has an IQ score between 74 and 126​.

P = 1- 95%

P = 5%

Therefore 5% of people has an IQ score less than 74 or greater than 126.

(c)

\overline{x}-3\sigma=100-3(13)=61

\overline{x}+3\sigma=100+3(13)=139

[\overline{x}-3\sigma,\overline{x}+3\sigma]=[61,139]

Using empirical rule we can say that 99.7% of people has an IQ score between 61 and 139​.

The percentage of people has an IQ score less than 61 or greater than 139 is

P = 1- percent of people has an IQ score between 61 and 139​.

P = 1- 99.7%

P = 0.3%

The percentage of people has an IQ score greater than 139​ is

P=\frac{1}{2}(0.3\%)=0.15\%

Therefore 0.15% of people has an IQ score greater than 139​.

5 0
4 years ago
A grid shows the positions of a subway stop and your house. The subway stop is located at (7, -6) and your house is located at (
Yuri [45]

So the distance between subway stop and house is 19 units

Step-by-step explanation:

The distance formula will be used to calculate the distance between home and subway.

d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}

Here (x1,y1) are the coordinates of first point

and

(x2,y2) are the coordinates of second point

Given

(x1,y1) = (7, -6)

(x2,y2) = (-9,5)

Putting the values in the formula

d=\sqrt{(-9-7)^2+(5-(-6))^2} \\=\sqrt{(-16)^2+(5+6)^2} \\=\sqrt{256+(11)^2}\\=\sqrt{256+121}\\=\sqrt{377}\\=19.41\ units

Rounding off to nearest unit gives us 19.

So the distance between subway stop and house is 19 units

Keywords: Distance, distance formula

Learn more about distance at:

  • brainly.com/question/1859222
  • brainly.com/question/1993757

#LearnwithBrainly

6 0
3 years ago
In one type of state lottery 5 distinct numbers are picked from 1,2,3,...,40 uniformly at random.
belka [17]

Answer: a) 1 / ⁴⁰C₅ b)  0.33

Step-by-step explanation:

a) The sample space consists of all numbers 1-40.

Since any of the number can be taken from the sample space  so each of five 5 distinct numbers we take has equal probability of occurring. So probability of each 5 numbers set we take will be equal to 1 / ⁴⁰C₅

b)

If we pick exactly 3 even number then that means other 2 will be odd.

So, we have sample space of 40 numbers out of which 20 are even and 20 are odd.

Now we have to pick 3 even out of 20 and 2 odd out of 20.

Probability = ²⁰C₃ * ²⁰C₂ / ⁴⁰C₅

Probability= 0.33

4 0
3 years ago
Katherine is considering two new cell phone plans. She doesn't want to spend more for minutes she won't use. One plan allows up
mojhsa [17]

Answer:

The first plan of $49 will be best plan for her.

Step-by-step explanation:

Katherine used 1479 minutes call in the last 6 months.

So, the average monthly call that Katherine made is \frac{1479}{6} =246.5 minutes.

Now, there are two plans for mobile recharge.

One is 250 minutes call time for $49 and the other is 350 minutes call time for $65.

Since 246.5 < 250 and Katherine does not want to spend more for minutes she won't use, then the first plan of $49 will be the best plan for her. (Answer)

8 0
3 years ago
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