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3 years ago

13

Find the volume of a rectangular fish tank with dimensions of 14 feet long,8 feet wide, and 6

1 answer:

Evgesh-ka [11]3 years ago

7 0

672

i need 29 characters that’s why I’m typing this part

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The weight of 10,000 identical samples of a substance is 100 pounds. What is the weight of 10 samples?

Misha Larkins [42]

The answer to the problem is .1

7 0

4 years ago

The radius of a cone is increasing at a constant rate of 7 meters per minute, and the volume is decreasing at a rate of 236 cubi

storchak [24]

Answer:

The rate of change of the height is 0.021 meters per minute

Step-by-step explanation:

From the formula

$V = \frac{1}{3}\pi r^{2}h$

Differentiate the equation with respect to time t, such that

$\frac{d}{dt} (V) = \frac{d}{dt} (\frac{1}{3}\pi r^{2}h)$

$\frac{dV}{dt} = \frac{1}{3}\pi \frac{d}{dt} (r^{2}h)$

To differentiate the product,

Let r² = u, so that

$\frac{dV}{dt} = \frac{1}{3}\pi \frac{d}{dt} (uh)$

Then, using product rule

$\frac{dV}{dt} = \frac{1}{3}\pi [u\frac{dh}{dt} + h\frac{du}{dt}]$

Since $u = r^{2}$

Then, $\frac{du}{dr} = 2r$

Using the Chain's rule

$\frac{du}{dt} = \frac{du}{dr} \times \frac{dr}{dt}$

∴ $\frac{dV}{dt} = \frac{1}{3}\pi [u\frac{dh}{dt} + h(\frac{du}{dr} \times \frac{dr}{dt})]$

Then,

$\frac{dV}{dt} = \frac{1}{3}\pi [r^{2} \frac{dh}{dt} + h(2r) \frac{dr}{dt}]$

Now,

From the question

$\frac{dr}{dt} = 7 m/min$

$\frac{dV}{dt} = 236 m^{3}/min$

At the instant when $r = 99 m$

and $V = 180 m^{3}$

We will determine the value of h, using

$V = \frac{1}{3}\pi r^{2}h$

$180 = \frac{1}{3}\pi (99)^{2}h$

$180 \times 3 = 9801\pi h$

$h =\frac{540}{9801\pi }$

$h =\frac{20}{363\pi }$

Now, Putting the parameters into the equation

$\frac{dV}{dt} = \frac{1}{3}\pi [r^{2} \frac{dh}{dt} + h(2r) \frac{dr}{dt}]$

$236 = \frac{1}{3}\pi [(99)^{2} \frac{dh}{dt} + (\frac{20}{363\pi }) (2(99)) (7)]$

$236 \times 3 = \pi [9801 \frac{dh}{dt} + (\frac{20}{363\pi }) 1386]$

$708 = 9801\pi \frac{dh}{dt} + \frac{27720}{363}$

$708 = 30790.75 \frac{dh}{dt} + 76.36$

$708 - 76.36 = 30790.75\frac{dh}{dt}$

$631.64 = 30790.75\frac{dh}{dt}$

$\frac{dh}{dt}= \frac{631.64}{30790.75}$

$\frac{dh}{dt} = 0.021 m/min$

Hence, the rate of change of the height is 0.021 meters per minute.

3 0

3 years ago

About two twenty-fifths of the male population in the world cannot distinguish red from green. If there are fourteen boys in the

solniwko [45]

About 175 ninth grade boys. 2/25 is equal to 0.08. if we take the 14 students and divide it by 0.08, we can get the total of 175 ninth grade boys.

6 0

3 years ago

a glass of jar contains 1 red, 3 green and 2 blue marbles. asingle marble is chosen at random from the jar and its color is reco

lubasha [3.4K]

hi,

first let's count the marbles : 1+3+2 = 6

so picking a red is 1/6

a green is : 3/6

a bleu is : 2/6

4 0

4 years ago

One number is 8 times another number. The numbers are both positive and have a difference of 70. Find the numbers. Which of the

worty [1.4K]

Let, the first (smaller) number = x
Larger number = 8x
Then, 8x - x = 70
7x = 70
x = 70/7
x = 10
& 8(10) = 80

In short, Your Numbers would be, 10 & 80

Hope this helps!

4 0

3 years ago