Help if you can, thanks.

An hourglass consists of two sets of congruent composite figures on either end. Each composite figure is made up of a cone and a

belka [17]

Answer: third option 268.8

Explanation:

For this kind of proble it is very important that you attach the figure because it contains important information to understand the question.

I have attached the figure for better understanding.

1) The top portion (and the bottom is congruent but rotated 180°) of the hourglass is a figure equivalent to a cylinder on top and a cone on bottom.

So the total volume contained in the top portion is the volume of a cylinder + the volume of a cone.

This is how you calculate the volume of the top portion:

1) The height of the cylinder is 54 mm - 18 mm = 36 mm

2) The formula for the volume of a cylinder is V = π (radius)^2 * height

radius = 8 mm
height = 36 mm

=> V = π(8mm)^2 * 36 mm = 2304π (mm)^3

3) The formula for the volume of a cone is V = (1/3)π(radius)^2 * height

radius = 8 mm
height = 18 mm

V = (1/3)π(8mm)^2 * 18 mm = 384π (mm)^3

4) The total volume of the top portion is volumen of the cylindrical part + voume of the cone:

Total voluem = 2304π (mm)^3 + 384π (mm)^3 = 2688π (mm)^3

5) To find the number of seconds <span>it take until all of the sand has dripped to the bottom of the hourglass you have to divide the total volumen of sand by the rate:

time in seconds = total volume of sand / rate of dripping

time in seconds = [2688 π (mm)^3 ] / [10π (mm)^3 / s] = 268.8 s

That is the answer: 268.8 s
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4 0

3 years ago

Read 2 more answers

Two shapes that represent the cross-sections

777dan777 [17]

Answer:

it's the square and the rectangle

3 0

2 years ago

Which trinomials are perfect square trinomials?

taurus [48]

You can know a perfect square trinomial:

i) if the coefficient of a² = 1.

ii) If you divide the middle number coefficient by 2 and you square it you get the last term.

Take for example the first option:

For all the options, the coefficient of a² = 1

a² + 4a + 16.

Coefficient of a = 4.
4/2 = 2
2² = 4, this does not equal the last term so it is not a perfect square trinomial.

a² + 14a + 49.

Coefficient of a = 14.
14/2 = 7
7² = 49, this is equal the last term so it is a perfect square trinomial.
And the perfect square is (a +7)²

Similarly if you test the last option.

a² + 26a + 169.

Coefficient of a = 26.
26/2 = 13
13² = 169, this is equal the last term so it is a perfect square trinomial.
And the perfect square is (a +13)²

So the only two options are: a² + 14a + 49 and a² + 26a + 169.

Other options do not pass this test.

3 0

2 years ago

Read 2 more answers

Determine the equation for the quadratic relationship graphed below.

kap26 [50]

Answer:

$\large \boxed{\sf \bf \ \ y=3x^2-6x-1 \ \ }$

Step-by-step explanation:

Hello, please consider the following.

We can read from the graph that the vertex is (1,-4) , it means that the equation is, a being a real number.

$y=a(x-1)^2-4$

And the point (0,-1) is on the graph so we can write.

$a\cdot 1^2-4=-1 \\\\a-4+4=-1+4\\\\a = 3$

So the equation is.

$y=3(x-1)^2-4\\\\=3(x^2-2x+1)-4\\\\=3x^2-6x+3-4\\\\=3x^2-6x-1\\\\=\boxed{3}x^2\boxed{-6}x\boxed{-1}$

Hope this helps.

Do not hesitate if you need further explanation.

Thank you

6 0

3 years ago

In January 2015, the Pew Research Center reported results from one of their surveys. "Asked about whether vaccines for childhood

scZoUnD [109]

Considering the margin of error, it is found that the 95% confidence interval for the percentage of adults who say vaccines should be required is (64.9%, 71.1%).

<h3>What is a confidence interval?</h3>

It is given by the sample statistic plus/minus the margin of error.

In this problem, 68% of adults say such vaccines should be required, with a margin of error of 3.1%, hence:

68% - 3.1% = 64.9%.

68% + 3.1% = 71.1%.

The 95% confidence interval for the percentage of adults who say vaccines should be required is (64.9%, 71.1%).

More can be learned about confidence intervals at brainly.com/question/25890103

3 0

2 years ago