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3 years ago

25% of what number is 21

Mathematics

2 answers:

Sergio [31]3 years ago

8 0

21 is 25% of 84.......

makkiz [27]3 years ago

3 0

84 because 21 times 4 equals 84

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Pyramid A has a triangular base where each side measures 4 units and a volume of 36 cubic units. Pyramid B has the same height,

omeli [17]

Answer:

The volume of pyramid B is 81 cubic units

Step-by-step explanation:

Given

Pyramid A

$s = 4$ -- base sides

$V = 36$ -- Volume

Pyramid B

$s = 6$ --- base sides

Required

Determine the volume of pyramid B [Missing from the question]

From the question, we understand that both pyramids are equilateral triangular pyramids.

The volume is calculated as:

$V = \frac{1}{3} * B * h$

Where B represents the area of the base equilateral triangle, and it is calculated as:

$B = \frac{1}{2} * s^2 * sin(60)$

Where s represents the side lengths

First, we calculate the height of pyramid A

For Pyramid A, the base area is:

$B = \frac{1}{2} * s^2 * sin(60)$

$B = \frac{1}{2} * 4^2 * \frac{\sqrt 3}{2}$

$B = \frac{1}{2} * 16 * \frac{\sqrt 3}{2}$

$B = 4\sqrt 3$

The height is calculated from:

$V = \frac{1}{3} * B * h$

This gives:

$36 = \frac{1}{3} * 4\sqrt 3 * h$

Make h the subject

$h = \frac{3 * 36}{4\sqrt 3}$

$h = \frac{3 * 9}{\sqrt 3}$

$h = \frac{27}{\sqrt 3}$

To calculate the volume of pyramid B, we make use of:

$V = \frac{1}{3} * B * h$

Since the heights of both pyramids are the same, we can make use of:

$h = \frac{27}{\sqrt 3}$

The base area B, is then calculated as:

$B = \frac{1}{2} * s^2 * sin(60)$

Where

$s = 6$

So:

$B = \frac{1}{2} * 6^2 * sin(60)$

$B = \frac{1}{2} * 36 * \frac{\sqrt 3}{2}$

$B = 9\sqrt 3$

So:

$V = \frac{1}{3} * B * h$

Where

$B = 9\sqrt 3$ and $h = \frac{27}{\sqrt 3}$

$V = \frac{1}{3} * 9\sqrt 3 * \frac{27}{\sqrt 3}$

$V = \frac{1}{3} * 9 * 27$

$V = 81$

6 0

3 years ago

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What is the correct value of x in the equation 2x + 3= 6

Brrunno [24]

Answer:

x=(3/2) OR 1.5

Step-by-step explanation:

2x+3=6

2x=6-3

2x=3

x=(3/2) OR 1.5

5 0

2 years ago

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Find the amount financed and the finance charge in dollars for the following problem. Choose the correct answers.

diamong [38]

$350 * 30/100 = $ 105 which is down payment.

$350 - $105 = $245 which is left.

But he will pay $24.50 * 12 = $294 instead.

$294 - $245 = $49

He will pay $49 more.

He paid $105 as down payment and will pay $294 more with 12 months.

Total will be $105 + $294 = $399

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3 years ago

Explain the the mistake in the student work

jeka94

He needed to divide instead of subtracting it on the last step.

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3 years ago

Marcel is performing the first test on his company's new electric car. During the test, the electric car reaches a maximum speed

valentina_108 [34]

Answer:

C. The electric car is not moving at 0 seconds and 12 seconds.

Step-by-step explanation:

Given:

The table given is:

x 0 2 4 6 8 10 12

y 0 45 72 81 72 45 0

From the above table, we observe that the car starts from rest and its speed increases from 0 to 6 seconds, the maximum speed being 81 mph.

After 6 seconds, the speed of the car goes on decreasing till it stops at time equal to 12 seconds.

So, the speed of the car at the start when $x=0$ is 0 mph as it is at rest at that time.

Also, when the time is $x=12\ s$ , the car has come to a stop and thus its speed has reduced to 0 mph again. So, the car is not moving after 12 seconds.

From the above conclusion, we can say that only option C is correct.

The electric car is not moving at 0 seconds and 12 seconds.

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2 years ago

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