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Greeley [361]
3 years ago
9

Solve the system by substitution. y = -3x + 4 y = -7x Submit Answer

Mathematics
1 answer:
iVinArrow [24]3 years ago
5 0

Answer:

{y,x} = {7,-1}

Step-by-step explanation:

(-7x) + 3x = 4

- 4x = 4

 4x = - 4

x = - 1

   y = -7x

   x = -1

   y = -7(-1) = 7

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Every evening Jenna empties her pockets and puts her change in a jar. At the end of the week she counts her money. One week she
Sergeeva-Olga [200]
A) .10 d + .25 q = 7.75
B) d + q = 40

Multiplying B) by -.10
B)  -.10d -.10q = -4.0
Then adding this to A)
A) .10 d + .25 q = 7.75
.15q = 3.75

Quarters = 25
Therefore, dimes = 15
***************************************************
Double-Check
A) .10 d + .25 q = 7.75
A) .10 * 15 d + .25 * 25 = 7.75
A) 1.50 + 6.25 = 7.75

Correct!!


6 0
2 years ago
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Ghella [55]

Answer:

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Step-by-step explanation:

5 0
2 years ago
Find the determinant of the following matrix. [1 -2] [3 4]​
Andrew [12]

Answer:

10

Step-by-step explanation:

[1 -2]

[3 4]

We can obtain the determinant of the above matrix by doing the following:

Determinant =(1 × 4) – (3 × –2)

Determinant = 4 – – 6

Determinant = 4 + 6

Determinant = 10

Thus, the determinant of the above matrix is 10

8 0
2 years ago
An experiment to investigate the survival time in hours of an electronic component consists of placing the parts in a test cell
mixer [17]

Answer:

a) The sample mean is of 49 and the sample standard deviation is of 11.7.

b) The range of the true mean at 90% confidence level is of 9.62 hours.

c) The prediction interval, at a 90% confidence level, of it's failure time is between 39.38 hours and 58.62 hours.

Step-by-step explanation:

Question a:

Sample mean:

\overline{x} = \frac{34+40+46+49+61+64}{6} = 49

Sample standard deviation:

s = sqrt{\frac{(34-49)^2+(40-49)^2+(46-49)^2+(49-49)^2+(61-49)^2+(64-49)^2}{5}} = 11.7

The sample mean is of 49 and the sample standard deviation is of 11.7.

b)Determine the range of the true mean at 90% confidence level.

We have to find the margin of error of the confidence interval. Since we have the standard deviation for the sample, the t-distribution is used.

The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So

df = 6 - 1 = 5

90% confidence interval

Now, we have to find a value of T, which is found looking at the t table, with 5 degrees of freedom(y-axis) and a confidence level of 1 - \frac{1 - 0.9}{2} = 0.95. So we have T = 2.0.150

The margin of error is:

M = T\frac{s}{\sqrt{n}}

In which s is the standard deviation of the sample and n is the size of the sample. So

M = 2.0150\frac{11.7}{\sqrt{6}} = 9.62

The range of the true mean at 90% confidence level is of 9.62 hours.

(c)If a seventh sample is tested, what is the prediction interval (90% confidence level) of its failure time.

This is the confidence interval, so:

The lower end of the interval is the sample mean subtracted by M. So it is 49 - 9.62 = 39.38 hours.

The upper end of the interval is the sample mean added to M. So it is 49 + 9.62 = 58.62 hours.

The prediction interval, at a 90% confidence level, of it's failure time is between 39.38 hours and 58.62 hours.

4 0
2 years ago
An average swimming pool contains 19200 gallons of water. The pool needs drained at the end of the summer. Water drains from the
Sergeu [11.5K]

Answer:

The answer is

D. V= 19200- 12t

Step-by-step explanation:

in this problem, we already know that the pool contains 19200 gallons of water

and the pool is draining at 12 gallons per minutes, hence the volume is decreasing at that rate

Therefore for t minutes it will decrease by 12t

hence the volume after t minutes will be

V= 19200-12t

7 0
3 years ago
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