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4 years ago

14

Harold bought 3 pounds od red applesand 4.2 pounds of green apples from Blue Star Company,where both kinds of apples were $1.75

a pound.How much did Harold spend on apples?

1 answer:

alexandr1967 [171]4 years ago

8 0

3(1.45)+4.2(1.75)= 5.25+7.35= 12.6 therefore Harold spent $12.60 on apples.

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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

The table shows locations on a map.

Nina [5.8K]

Answer:

The table shows locations on a map.

<u>Place</u>

park
farmers market
post office
bus stop

<u>Location</u>

(-2,2)
(-2,3)
(2, 2)
(6,-3)

Which places on the map are 4 units apart?

O the park and the farmer's market

O the farmers market and the bus stop

<em><u>✓</u></em> <em><u>the post office and the park</u></em>

O the post office and the bus stop

Step-by-step explanation:

Distance :---

$→ \sqrt{ {(2 - ( -2 ))}^{2} + {(2 - 2)}^{2} } \\ = \sqrt{ {4}^{2} + {0}^{2} } = \sqrt{ {4}^{2} } = \boxed{4 \: units}$

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3 years ago

The sound intensity of rustling leaves is 100 times the reference intensity. Use your graph to determine the sound intensity of

wariber [46]

The sound intensity of rustling leaves, y = 20 decibels

<u>Step-by-step explanation:</u>

y = 10logx

The sound intensity of rustling leaves is 100 times the reference intensity.

x = ratio of intensity of sound to reference to intensity

x = 100:1 or x = 100

y = 10 log(100) = 10 * 2 = 20 decibels

y = 20 decibels

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3 years ago

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aliya0001 [1]

Answer:

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Step-by-step explanation:

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Setler79 [48]

Answer:

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Step-by-step explanation:

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3 * 3 - (-8)/4

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3 * 4 - 4/4

12 - 1 = 11

Both ordered pairs equals to 11, therefore, they're both solutions to the equation.

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3 years ago