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How do you solve this using substitution method 17x+7y=20 Y=20x-42

Nutka1998 [239]

Answer:

17 x + 7 y = 20

y =20x - 42

17 x + 7(20x - 42) = 20

17x + 140x - 294 = 20

157 x = 20 + 294

157x ÷ 157 = 314 ÷ 157

x = 2

y = 20x - 42 

y = 20 (2) - 42

y = 40 - 42

y = -2

there for x = 2 and y = -2 is the solution 

4 0

2 years ago

The National Center for Educational Statistics surveyed 5400 college graduates about the lengths of time required to earn their

fenix001 [56]

Answer:

The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

$M = 1.645*\frac{1.9}{\sqrt{4500}} = 0.04$

The lower end of the interval is the sample mean subtracted by M. So it is 5.4 - 0.04 = 5.36 years.

The upper end of the interval is the sample mean added to M. So it is 5.4 + 0.04 = 5.44 years.

The 90% confidence interval for the mean time required by all college graduates is between 5.36 years and 5.44 years.

3 0

3 years ago

19. Rick shared his bag of grapes withfriends. He gave /210of the bag to Melissaand /410 of the bag to Ryan. What fractionof the

kvv77 [185]

Rick started with 10/10 of the grapes because he had all of them at the start.

Then he gave 2/10 and 4/10 of the grapes away.

10/10 - 2/10 - 4/10 = 4/10 = 2/5 left

answer: Rick had 2/5 of the grapes left.

4 0

3 years ago

A spheres radius is multiplied by 2. How is it’s surface area affected

dexar [7]

Answer:

The surface area is multiplied by 3.

Step-by-step explanation:

If r is the radius of a sphere its surface area = 4(pi)r^2. If the radius is doubled then its surface area = 4(pi)(2r)^2 = 4*4(pi)r^2. So the surface area becomes 4-fold or the increase in surface area is 300%.

3 0

3 years ago

Need help : a^2-7a =0

Sladkaya [172]

Answer:

a = 0 or a = -7

Step-by-step explanation:

We are going to solve this quadratic equation by factorizing.

a² - 7a = 0

a(a - 7) = 0

a = 0 or a - 7 = 0

a = 0 or a = -7

7 0

3 years ago