Will give the brainliest for quick answer please!

Solve the following using substitution method

Wewaii [24]

Solution :

2a + 2b = 7 ...1)

4a + 3b = 12 ...2)

In equation, 1)

a = (7 - 2b)/2 ...3)

Putting value of a in equation 2) we get :

4 × (7 - 2b)/2 + 3b = 12

2( 7 - 2b ) + 3b = 12

14 - 4b + 3b = 12

b = 2

Putting value of b in 3) we get :

a = ( 7 - 2×2)/2

a = 3/2 = 1.5

Now,

2x - 3y = 16 ...5)

x + 2y = -6 ...6)

x = -6 - 2y

Putting above value of x in eq 5) , we get :

2( -6 - 2y ) - 3y = 16

-12 - 4y - 3y = 16

7y = -28

y = -4

x = -6 - ( 2× -4 )

x = 2

Hence, this is the required solution.

6 0

2 years ago

A chemist examines 12 sedimentary samples for bromide concentraction. The mean bromide concentration for the sample date is 0.43

Umnica [9.8K]

Answer:

a) $z = 1.645$

b) Lower endpoint: 0.422cc/m³

Upper endpoint: 0.452 cc/m³

Step-by-step explanation:

Population is approximately normal, so we can find the normal confidence interval.

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 $z = 1.645$ . This is the critical value, the answer for a).

Now, find 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.

$M = 1.645*\frac{0.0325}{\sqrt{12}} = 0.015$

The lower end of the interval is the sample mean subtracted by M. So it is 0.437 - 0.015 = 0.422cc/m³.

The upper end of the interval is the sample mean added to M. So it is 0.437 + 0.015 = 0.452 cc/m³.

b)

Lower endpoint: 0.422cc/m³

Upper endpoint: 0.452 cc/m³

4 0

3 years ago

The boeing 747 airplane is 250 feet in length. If a model of this plane is 8 inches long , what scale was used to create this mo

cluponka [151]

Answer: The wingspan is 36 m.

Using a proportion to solve this, we write the scale factor as a ratio first: 19/38, since 19 is the size of the model's length and 38 is the real length. For the second ratio, we have 18 for the size of the model wingspan and x for the real wingspan:

19/38 = 18/x

Cross multiply:

19*x = 38*18

19x = 684

8 0

3 years ago

Patty wants a triangle garden in her backyard for all of her vegetables. She

otez555 [7]

Answer:

Step-by-step explanation:

the hypothenuse is the largest side in the right triangle

we have 2 side, 7,8