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3 years ago

Rewrite the proportion 7:21 = 3:9 as a proportion using fractions.

Mathematics

2 answers:

Inessa [10]3 years ago

4 0

Answer:

1/3 ig

Step-by-step explanation:

VARVARA [1.3K]3 years ago

4 0

Answer: In this problem you want to rewrite the proportion 7:21 to 3:9.

First, a proportion is a relation between two quantities, this is if the proportion of A to B is 7:21, then you can represent it in a equation as:

7*A = 21*B

If you divide by the same number in both sides of the equation, you dont affect the equality, then if i divide both sides by 7, the equation turns into:

7*A/7 = 21*B/7

A = (21/7)*B = 3*B

Now if i multiply both sides by 3.

3*A = 3*(3*B) = 9*B

3A = 9*B

so now the proportion is 3:9.

Also, if you want to see if two proportions are equivalent, you need to see that quotients are the equal.

In this case 21/7 = 3, and 9/3 = 3.

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For this case we propose a system of equations. We have to:

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y: Let the variable that represents the number of quaters

We know that:

One dime equals 10 cents, $0.10

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According to the statement we have:

$x + y = 5\\0.10x + 0.25y = 1$

We multiply the first equation by -0.10:

$-0.10x-0.10y = -0.5$

We have the following equivalent system:

$-0.10x-0.10y = -0.5\\0.10x + 0.25y = 1$

We add the equations:

$-0.10x + 0.10x-010y + 0.25y = -0.5 + 1\\0.15y = 0.5\\y = \frac {0.5}{0.15}\\y = 3.33$

Approximately 3 quater coins

$x = 5-y = 5-3 = 2$

And two dimes

Answer:

3 quater

2 dimes

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3 years ago

What type of triangle is formed by joining the points D(7, 3), E(8, 1), and

soldi70 [24.7K]

Answer:

Step-by-step explanation:

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3 years ago

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3. A wall is 12 feet high. If its area is 132 sq ft, what is its

dalvyx [7]

B. 46 feet because 132/12=11 and 12+12+11+11=46

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2 years ago

g If a snowball melts so that its surface area decreases at a rate of 4 cm2/min, find the rate (in cm/min) at which the diameter

maks197457 [2]

Answer:

Rate of change of the diameter is equal to 0.053cm/min

Step-by-step explanation:

A snowball is of the shape of a sphere

Surface area of Sphere (S)= $4*pi*R^2$

Rate of change of surface area

dS/dt = -4 $cm^2/min$

the negative sign indicates the surface area is decreasing.

Radius = d/2 where d represents diameter

using this is the surface area equation

S = $4*pi*(d/2)^2$

= $pi*d^2$

dS/dt = 2*pi*d*d(d)/dt

4 = 2*pi*d*(d)/dt

d(d)/dt = 2/12*pi= $\frac{1}{6pi}$ cm/min

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2 years ago

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