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

4 years ago

Read 2 more answers

PLEASE HELP!!!!

Semmy [17]

You should put 4 as x, -3 as y and a as slope to make an equation :
$- 3 = a \times 4$
then you can find the slope and the correct equation of the line :

the slope is :
$- 3 = 4a \\ a = \frac{ - 3}{4}$
so the equation of the line will be
$y = \frac{ - 3}{4} x$
D is true
hope this helps

5 0

3 years ago

The sum of three consecutive integers is -126. What are the integers?

Aleks04 [339]

First Set x to the value of the smallest integer.

so the value of x for each increasing term can be generalized as follows

x +

$x + x + 1 + x + 2 = - 126 \\$