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4 years ago

Please help with 1-9 43 points

Mathematics

2 answers:

Paul [167]4 years ago

7 0

Remark

I'll do two from each group, leaving you with 1. I just leave the answer for the one I don't do or a hint it it is long. That's more than we are instructed to do (which is three parts per posted question).

One

Two ratios form a proportion because they both equal the same thing when you reduce them to the point where the ratios are prime to each other.

3/4 = 12/16

3/4 can't be reduced any further. When both 12 and 16 are divided by 4, the result is 3/4

Two

Formula

Sale Price/Original Price = 3/4

Solve

Sale Price / 64 = 3/4 Multiply both sides by 64

Sale Price = (3/4)*64

Sale Price = 48

Three

682 Trillion atoms of hydrogen.

Four

Formula

rotations / 40 seconds = rotations / second

Solve

2000 / 40 seconds = rotations / 1 second Just divide

50 rotations/1 second = rotations / second.

Five

Formula

Herd of cows / Total pounds of milk = 1 cow / pounds of milk

Given

Herd = 12

pounds total = 224998

Solve

12/224998 = 1 / x Cross multiply

12x = 224998

x = 18750 pounds of milk for 1 cow.

Six

0.5 m in 1 second.

Seven

Formula

Pages / hour = pages / minute

pages / hour = 4.5

1 hour = 60 minutes.

Solve

4.5 / 1 hour. But 1 hour = 60 min

4.5 pages / 60 min = 0.075 pages per minute.

Note this is not a true proportion. You just have to know how it is done.

Eight

This is also not a true proportion. The best way to do this is called unit analysis.

$\dfrac{18feet}{2seconds} * \dfrac{1 mile}{5280 feet}\dfrac{3600sec}{1hour}$

Each set of units on the right will cancel with a set of units on the left until all that you area left with is miles / hour. Then just multiply the numerator numbers together and denominator numbers together.

numerator: 18 * 1 * 3600 = 64800

denominator: 2 * 5280 * 1 = 10560

Now divide the numerator by the denominator.

answer: numerator/denominator = 64800/10560 = 6.14 miles per hour.

Nine

Note: there are 1760 yards in a mile.

1 gallon will take you 32000 yards or 18 miles. Do this the same way eight was done.

shtirl [24]4 years ago

4 0

Answer: 1 gallon will take you 32000 yards or 18 miles. Do this the same way eight was done.

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3 years ago

HELP ASAP (Geometry)

Andrei [34K]

1) Parallel line: $y=-2x-3$

2) Rectangle

3) Perpendicular line: $y = 0.5x + 2.5$

4) x-coordinate: 2.7

5) Distance: $d=\sqrt{(4-3)^2+(7-1)^2}$

6) 3/8

7) Perimeter: 12.4 units

8) Area: 8 square units

9) Two slopes of triangle ABC are opposite reciprocals

10) Perpendicular line: $y-5=-4(x-(-1))$

Step-by-step explanation:

The equation of a line is in the form

$y=mx+q$

where m is the slope and q is the y-intercept.

Two lines are parallel to each other if they have same slope m.

The line given in this problem is

$y=-2x+7$

So its slope is $m=-2$ . Therefore, the only line parallel to this one is the line which have the same slope, which is:

$y=-2x-3$

Since it also has $m=-2$

We can verify that this is a rectangle by checking that the two diagonals are congruent. We have:

- First diagonal: $d_1 = \sqrt{(-3-(-1))^2+(4-(-2))^2}=\sqrt{(-2)^2+(6)^2}=6.32$

- Second diagonal: $d_2 = \sqrt{(1-(-5))^2+(0-2)^2}=\sqrt{6^2+(-2)^2}=6.32$

The diagonals are congruent, so this is a rectangle.

Given points A (0,1) and B (-2,5), the slope of the line is:

$m=\frac{5-1}{-2-0}=-2$

The slope of a line perpendicular to AB is equal to the inverse reciprocal of the slope of AB, so:

$m'=\frac{1}{2}$

And using the slope-intercept for,

$y-y_0 = m(x-x_0)$

Using the point $(x_0,y_0)=(7,1)$ we find:

$y-1=\frac{1}{2}(x-7)$

And re-arranging,

$y-1 = \frac{1}{2}x-\frac{7}{2}\\y=\frac{1}{2}x-\frac{5}{2}\\y=0.5x-2.5$

The endpoints of the segment are X(1,2) and Y(6,7).

We have to divide the sgment into 1/3 and 2/3 parts from X to Y, so for the x-coordinate we get:

$x' = x_0 + \frac{1}{3}(x_1 - x_0) = 1+\frac{1}{3}(6-1)=2.7$

The distance between two points $A(x_A,y_A)$ and $B(x_B,y_B)$ is given by

$d=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}$

In this problem, the two points are

E(3,1)

F(4,7)

So the distance is given by

$d=\sqrt{(4-3)^2+(7-1)^2}$

We have:

A(3,4)

B(11,3)

Point C divides the segment into two parts with 3:5 ratio.

The distance between the x-coordinates of A and B is 8 units: this means that the x-coordinate of C falls 3 units to the right of the x-coordinate of A and 5 units to the left of the x-coordinate of B, so overall, the x-coordinate of C falls at

$\frac{3}{3+5}=\frac{3}{8}$

of the distance between A and B.

To find the perimeter, we have to calculate the length of each side:

$d_{EF}=\sqrt{(x_E-x_F)^2+(y_E-y_F)^2}=\sqrt{(-1-2)^2+(6-4)^2}=3.6$

$d_{FG}=\sqrt{(x_G-x_F)^2+(y_G-y_F)^2}=\sqrt{(-1-2)^2+(3-4)^2}=3.2$

$d_{GH}=\sqrt{(x_G-x_H)^2+(y_G-y_H)^2}=\sqrt{(-1-(-3))^2+(3-3)^2}=2$

$d_{EH}=\sqrt{(x_E-x_H)^2+(y_E-y_H)^2}=\sqrt{(-1-(-3))^2+(6-3)^2}=3.6$

So the perimeter is

p = 3.6 + 3.2 + 2 + 3.6 = 12.4

The area of a triangle is

$A=\frac{1}{2}(base)(height)$

For this triangle,

Base = XW

Height = YZ

We calculate the length of the base and of the height:

$Base =XW=\sqrt{(x_X-x_W)^2+(y_X-y_W)^2}=\sqrt{(6-2)^2+(3-(-1))^2}=5.7$

$Height =YZ=\sqrt{(x_Y-x_Z)^2+(y_Y-y_Z)^2}=\sqrt{(7-5)^2+(0-2)^2}=2.8$

So the area is

$A=\frac{1}{2}(XW)(YZ)=\frac{1}{2}(5.7)(2.8)=8$

A triangle is a right triangle when there is one right angle. This means that two sides of the triangle are perpendicular to each other: however, two lines are perpendicular when their slopes are opposite reciprocals. Therefore, this means that the true statement is

"Two slopes of triangle ABC are opposite reciprocals"

10)

The initial line is

$y=\frac{1}{4}x-6$