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3 years ago

40% of what number is 84?

Mathematics

2 answers:

Fynjy0 [20]3 years ago

4 0

Answer:

210

Step-by-step explanation:

84 / .40 = 210

(to check)

210 X .40 = 84

lord [1]3 years ago

3 0

Answer:

210

Step-by-step explanation:

When working out a percentage for example 20% of 40, I follow 2 simple rules to get to the answer.

⇒ Multiply the percentage by the other number

⇒ Divide the multiplied number by 100

So for the example, Find 20% of 40

⇒ Multiply the percentage by the other number

→ 20 × 40 = 800

⇒ Divide the multiplied number by 100

→ 800 ÷ 100 = 8

So 20% of 40 is 8.

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Using the method above we can set up an equation. We will call the number we want to find 'x'

⇒ Form the equation

→ $\frac{40*x}{100} =84$

⇒ Multiply both sides by 100 to isolate $40*x$

→ $40*x=8400$

⇒ Divide both sides by 40 to isolate x

→ $x = 210$

So we know that 40% of 210 is 84. We can use the method at the top to see if our solution is correct

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⇒ Multiply the percentage by the other number

⇒ Divide the multiplied number by 100

So, Find 40% of 210

⇒ Multiply the percentage by the other number

→ 40 × 210 = 8400

⇒ Divide the multiplied number by 100

→ 8400 ÷ 100 = 84

So 40% of 210 is 84.

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Is the relationship between 7,742 and 7,785 different in anyway?

timurjin [86]

Yes Because 7,785 is greater than 7,742.

5 0

3 years ago

In 6 years, Mariya will be as old as Vikram is now. In 2 years, Vikram will be three times older than Mariya. Find their ages no

Damm [24]

Answer:

Mariya is 1 year old

Vikram is 7 years old

Step-by-step explanation:

Here, we want to know the present ages of Mariya and Vikram.

Let the present age of Mariya be M and the present age of Vikram be V

From the question, we are told that in 6 years time, Mariya will be as old as Vikram is now

Thus, mathematically;

M + 6 = V ••••••(i)

Furthermore , in 2 years time Vikram will be 3 time older than Mariya

Mathematically;

( V + 2) = 3( M + 2)

V + 2 = 3M + 6

V = 3M + 6-2

V = 3M + 4 •••••••(ii)

So let’s equate the V

3m + 4 = m + 6

3m -m = 6-4

2m = 2

m = 1

But V = m + 6

V = 1 + 6

V = 7

3 0

3 years ago

If you are offered one slice from a round pizza (in other words, a sector of a circle) and the slice must have a perimeter of 24

VARVARA [1.3K]

Answer:

A 12 in diameter will reward you with the largest slice of pizza.

Step-by-step explanation:

Let $r$ be the radius and $\theta$ be the angle of a circle.

According with the graph, the area of the sector is given by

$A=\frac{1}{2}r^2\theta$

The arc lenght of a circle with radius $r$ and angle $\theta$ is $r \theta$

The perimeter of the pizza slice is composed of two straight pieces, each of length r inches, and an arc of the circle which you know has length s = rθ inches. Thus the perimeter has length

$2r+r\theta=24 \:in$

We need to express the area as a function of one variable, to do this we use the above equation and we solve for $\theta$

$2r+r\theta=24\\r\theta=24-2r\\\theta=\frac{24-2r}{r}$

Next, we substitute this equation into the area equation

$A=\frac{1}{2}r^2(\frac{24-2r}{r})\\A=\frac{1}{2}r(24-2r)\\A=12r-r^2$

The domain of the area is

$0$

To find the diameter of pizza that will reward you with the largest slice you need to find the derivative of the area and set it equal to zero to find the critical points.

$\frac{d}{dr} A=\frac{d}{dr}(12r-r^2)\\A'(r)=\frac{d}{dr}(12r)-\frac{d}{dr}(r^2)\\A'(r)=12-2r$

$12-2r=0\\-2r=-12\\\frac{-2r}{-2}=\frac{-12}{-2}\\r=6$

To check if $r=6$ is a maximum we use the Second Derivative test

if $f'(c)=0$ and $f''(c)$ , then f(x) has a local maximum at x = c.

The second derivative is

$\frac{d}{dr} A'(r)=\frac{d}{dr} (12-2r)\\A''(r)=-2$

Because $A''(r)=-2$ the largest slice is when r = 6 in.

The diameter of the pizza is given by

$D=2r=2\cdot 6=12 \:in$

A 12 in diameter will reward you with the largest slice of pizza.

3 0

3 years ago

5. trey made pasta in the Shape of a square ; He draws 2 lines to cut the pasta into smaller pieces The smaller pieces have L I

hodyreva [135]

Wouldn't it be. 8 pieces because you cut each sides into two pieces so like this. —|—. You'll end up having four square pieces, but count the pieces that creates an L shape.

best wishes good luck

7 0

3 years ago

Read 2 more answers

HELP ‼️‼️‼️‼️‼️‼️‼️‼️‼️‼️‼️WILL MARK BRAINLYEST‼️‼️‼️

Rainbow [258]

Answer:

8 one-dollar bills

3 five-dollar bills

2 ten-dollar bills

Step-by-step explanation:

Let x = # of one-dollar bills, y = # of five-dollar bills, and z = # of ten-dollar bills. Total amount in the wallet is $43, so the first equation would be 1x + 5y + 10z = 43. Next, there are 4 times as many one-dollar bills as ten-dollar bills, so x = 4z. There are 13 bills in total, so x + y + z = 13

x + 5y + 10z = 43

x = 4z

x + y + z = 13

x + 5y + 10z = 43

x + 0y - 4z = 0

x + y + z = 13

5y + 14z = 43

-y - 5z = -13

5y + 14z = 43

-5y - 25z = -65

-11z = -22

z = 2

x = 4z

x = 4*2 = 8

x + y + z = 13

8 + y + 2 = 13

10 + y = 13

y = 3

3 0

1 year ago