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4 years ago

Solve by substitution. Show each step of your work. 2x + y = 7 3x + 5y = 14

1 answer:

8 0

Alright...simple...showing all steps.. ;)

You have the equations...

2x+y=7
and
3x+5y=14

To be able to even solve for any of the variables...multiply the equations by...2...and..3...

2x+y=7----*3--> 6x+3y=21
and
3x+5y=14-----*2--->6x+10y=28

Thus,

6x+3y=21
-
6x+10y=28

=========

-7y=-7

y=1

Now, plug y back into any of the original equations....we'll use 2x+y=7 in this case....

2x+(1)=7

2x+1=7
-1 -1

2x=6

x=3

Thus, the point of intersection for these two equations is (3,1)

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We wish to give a 90% confidence interval for the mean value of a normally distributed random variable. We obtain a simple rando

coldgirl [10]

Answer: $(9.27025,\ 11.12975)$

Step-by-step explanation:

Given : Sample size : n= 9

Degree of freedom = df =n-1 =8

Sample mean : $\overline{x}=10.2$

sample standard deviation : $s= 1.5$

Significance level ; $\alpha= 1-0.90=0.10$

Since population standard deviation is not given , so we use t- test.

Using t-distribution table , we have

Critical value = $t_{\alpha/2, df}=t_{0.05 , 8}=1.8595$

Confidence interval for the population mean :

$\overline{x}\pm t_{\alpha/2, df}\dfrac{s}{\sqrt{n}}$

90% confidence interval for the mean value will be :

$10.2\pm (1.8595)\dfrac{1.5}{\sqrt{9}}$

$10.2\pm (1.8595)\dfrac{1.5}{3}$

$10.2\pm (1.8595)(0.5)$

$10.2\pm (0.92975)$

$(10.2-0.92975,\ 10.2+0.92975)$

$(9.27025,\ 11.12975)$

Hence, the 90% confidence interval for the mean value= $(9.27025,\ 11.12975)$

6 0

3 years ago

A piece of wood is designed in the same of a cone.

77julia77 [94]

Answer:

See explanation

Step-by-step explanation:

Volume of cone - volume of cylinder

[1/3π(6)²(14)] - [π(4)²(3)]

168π - 48π = 120π

6 0

3 years ago

A car was traveling 86 kilometers per hour.

ki77a [65]

Its easy to convert 86 kilometers per hour to meters per second :

Just divide the speed which is 86 by 3.6

86 divide 3.6 = 24 m/s or meter per second

8 0

3 years ago

Andrew fish tank holds 144 gallons of water. To clean the tank, he drains the water at a rate the water at a rate of 6 gallons p

Kobotan [32]

Answer:

8 minutes

Step-by-step explanation:

Since the level of the tank needs to be at two-thirds its original level, then this means that Andrew needs to drain only one-third of the fish tank. Therefore the amount of time it would take can easily be solved with this 2-step equation...

6t = 144 * $\frac{1}{3}$ .... first multiply the right side of the equation