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2 years ago

X + 7y = 21 x + 4y = 15 Solve the simultaneous equations

Mathematics

2 answers:

Mariulka [41]2 years ago

8 0

Answer:

x = 7, y = 2

Explanation:

equations given:

x + 7y = 21

x + 4y = 15

make "x" the subject:

x + 7y = 21

x = 21 - 7y .........equation 1

x + 4y = 15

x = 15 - 4y .......equation 2

Solving both the equations simultaneously:

15 - 4y = 21 - 7y

-4y + 7y = 21 - 15

3y = 6

y = 6 ÷ 3

y = 2

If y is 2

Then x = 21 -7y;

x = 21 - 7(2)

x = 21 - 14

x = 7

Yuliya22 [10]2 years ago

6 0

x + 7y= 21

7 goes to RHS = X+ y = 21/7-3

x + 4y = 15

4 goes to RHS= x+y = 15/4 = 3.75

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2 years ago

Scores on the test are normally distributed with a mean of 79 and a standard deviation of 8.4. Find the numerical limits for a B

Oksanka [162]

This is not the question, the correct question is:

A humanities professor assigns letter grades on a test according to the following scheme. A: Top 6% of scores B: Scores below the top 6% and above the bottom 59% C: Scores below the top 41% and above the bottom 17% D: Scores below the top 83% and above the bottom 7% F: Bottom 7% of scores.

Scores on the test are normally distributed with a mean of 79 and a standard deviation of 8.4. Find the numerical limits for a B grade. Round your answers to the nearest whole number, if necessary.

Answer: The numerical limits for grade B is 81 and 92

Step-by-step explanation:

Given that

mean Ж = 79

Standard deviation S = 8.4

B: Scores below the top 6% and above the bottom 59%

To find the numerical value for Grade B

Below the top bottom 6% ( 0.06) is

p ( X < Ж ) = 1 - 0.06

p ( X < Ж ) = 0.94

therefore

P( (X - ц)/S < (X - Ж) / S)) = 0.94

(X - 79) / 8.4 = 1.5548 ( from normal distribution table )

X - 79 = 13.0603

X = 13.0603 + 79

X = 92.06 ≈ 92 ( nearest whole number)

Above bottom 59% ( 0.59) is

p ( X < Ж ) = 0.59

therefore

P( (X - ц)/S < (X - Ж) / S)) = 0.59

(X - 79) / 8.4 = 0.2275 ( from normal distribution table )

X - 79 = 1.9114

X = 1.9114 + 79

X = 80.91 ≈ 81 ( nearest whole number)

So the numerical limits for grade B is 81 and 92

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2 years ago

Find the height (h) of the triangle shown.

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3 years ago

I’m Atlanta, the tax on a property assessed at $930,000 is $19,530. If tax rates are proportional in this city, how much would t

igomit [66]

Answer:

The tax on property assessed at $660,000 is $13860 .

Step-by-step explanation:

Given:

In Atlanta the tax on a property assessed at $930,000 is $19,530.

The tax rates are proportional to this city.

Now, to find the tax on a property assessed at $660,000.

So, we need to get the tax rate of Atlanta first.

Tax Rate = Tax / Property assessed × 100.

$Tax\ rate=\frac{19530}{930000} \times 100$

$Tax\ rate=0.021 \times 100$

$Tax\ rate=2.1\%$

According to question the tax rates are proportional.

So, for getting the tax in this city we use the same rate of Atlanta:

Tax = tax rate of property assessed.

$Tax = 2.1\% of\ \$660,000$

$Tax = \frac{2.1}{100}\times 660000.$

$Tax = 0.021\times 660000$

$Tax=\$13860$

Therefore, the tax on property assessed at $660,000 is $13860.

6 0

2 years ago