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3 years ago

4 tons of sawdust cost $3,120.00. What is the price per pound?

Mathematics

1 answer:

solmaris [256]3 years ago

4 0

0.39 dollars per pound

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The surface area of a cylinder is increasing at a rate of 9 pi square meters per hour. The height of the cylinder is fixed at 3

Alekssandra [29.7K]

Answer:

$9\pi \text{ cubic meters per hour}$

Step-by-step explanation:

Since, the surface area of a cylinder,

$A= 2\pi r^2 + 2\pi rh$ ................(1)

Where,

r = radius,

h = height,

If $A= 36\pi\text{ square meters}, h = 3\text{ meters}$

$36\pi = 2\pi r^2 + 2\pi r(3)$

$18 = r^2 + 3r$

$\implies r^2 + 3r - 18=0$

$r^2 + 6r - 3r - 18 = 0$ ( by middle term splitting )

$r(r+6)-3(r+6)=0$

$(r-3)(r+6)=0$

By zero product property,

r = 3 or r = - 6 ( not possible )

Thus, radius, r = 3 meters,

Now, differentiating equation (1) with respect to t ( time ),

$\frac{dA}{dt}= 4\pi r\frac{dr}{dt} +2\pi(r\frac{dh}{dt} + h\frac{dr}{dt})$

∵ h = constant, ⇒ dh/dt = 0,

$\frac{dA}{dt} = 4\pi r \frac{dr}{dt} +2\pi h \frac{dr}{dt}$

We have, $\frac{dA}{dt}=9\pi\text{ square meters per hour}, r = h = 3\text{ meters}$

$9\pi = 4\pi (3) \frac{dr}{dt}+2\pi (3)\frac{dr}{dt}$

$9\pi = (12\pi + 6\pi )\frac{dr}{dt}$

$9\pi = 18\pi \frac{dr}{dt}$

$\implies \frac{dr}{dt} =\frac{1}{2}\text{ meter per hour}$

Now,

Volume of a cylinder,

$V=\pi r^2 h$

Differentiating w. r. t. t,

$\frac{dV}{dt}=\pi ( r^2 \frac{dh}{dt}+h(2r)\frac{dr}{dt})=\pi ((3)(6) (\frac{1}{2})) = 9\pi \text{ cubic meters per hour}$

6 0

3 years ago

Will give thank,brainly and 5 stars!

konstantin123 [22]

The second and last one.

The second one multiplies the cost of each type of ticket by two, therefore saying that you wanted to buy two of each type of ticket.

The last one multiplies the cost of a single ticket of all three types and multiplies it by 2.

6 0

2 years ago

Read 2 more answers

PLEASE HELP ME WITH THIS

Mice21 [21]

Wha do u need help with

8 0

3 years ago

Help pls! 50 pts and brainliest!<br> tyyyy

sesenic [268]

Answer:

Step-by-step explanation:

(1/6)*60 = 10

(1/6)*450 = 75

Check your work

75/10 = 7.5

450/60 = 7.5

Correct!

6 0

3 years ago

Nikki can make 5 free throws in 8 attempts. If she continues this pattern, how many free throws can she 128 attempts? Show your

konstantin123 [22]

Step-by-step explanation:

80 free throws on 128 attempts

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3 years ago