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77julia77 [94]
2 years ago
12

A 10 cm thick grindstone is initially 200 cm in diameter, and it is wearing away at a rate of LaTeX: 50cm^3/hr. At what rate is

it's diameter decreasing
Mathematics
1 answer:
timurjin [86]2 years ago
8 0

Complete question is;

A 10 cm thick grindstone is initially 200 cm in diameter, and it is wearing away at a rate of 50 cm/hr. At what rate is its diameter decreasing?

Answer:

Diameter is decreasing at the rate of 5/(2πr) cm/hr

Step-by-step explanation:

We are told the stone is wearing away at a rate of 50 cm/hr. This means the volume is decreasing. Thus;

dV/dt = -50 cm/hr

Now, a grindstone is in the shape of a cylinder. Thus, volume of grindstone is;

V = πr²h

dV/dr = 2πrh

Now,to find the rate at which the diameter is decreasing, we'll write;

dr/dt = (dV/dt)/(dV/dr)

dr/dt = -50/(2πrh)

We are given;

Diameter = 200 cm

Radius; r = 200/2 = 100 cm

Thickness; h = 10 cm

Thus;

dr/dt = -50/(2π × r × 10)

dr/dt = -5/(2πr) cm/hr

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Of 560 samples of seafood purchased from various kinds of food stores in different regions of a country and genetically compared
frutty [35]

Answer:

a) (0.5256,0.5944)  

c) Criticism is invalid

Step-by-step explanation:

We are given the following in the question:

Sample size, n = 560

Proportion of mislabeled = 56%

\hat{p} = 0.56

a) 90% Confidence interval:

\hat{p}\pm z_{stat}\sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}}

z_{critical}\text{ at}~\alpha_{0.05} = \pm 1.64

Putting the values, we get:

0.56\pm 1.64(\sqrt{\dfrac{0.56(1-0.56)}{560}}) = 0.56\pm 0.0344\\\\=(0.5256,0.5944)

b) Interpretation of confidence interval:

We are 90% confident that the true proportion of all seafood in the country that is mislabeled or misidentified is between 0.5256 and 0.5944 that is 52.56% and 59.44%.

c) Validity of criticism

Conditions for validity:

np > 10\\n(1-p)>10

Verification:

560\times 0.56 = 313.6>10\\560(1-0.56) = 246.4>10

Both the conditions are satisfied. This, the criticism is invalid.

8 0
2 years ago
Emily is a songwriter who collects royalties on her songs whenever they are played in a commercial or a movie. Emily will earn $
Hitman42 [59]

Answer:

(6,2)

Step-by-step explanation:

Variable Definitions:

​x= the number of commercials

y= the number of movies

Each commercial earns Emily $50, so x commercials would earn her 50x dollars in royalties. Each movie earns Emily $150, so y movies would earn her 150y dollars in royalties. Therefore, the total royalties 50x+150y equals $600:

50x+150y=600

Since Emily's songs were played on 3 times as many commercials as movies, if we multiply 3 by the number of movies, we will get the number of commercials, meaning x equals 3y.

x=3y

Write System of Equations:

​50x+150y=600

x=3y

Solve for y in each equation:

1)  50x+150y=600

   150y=−50x+600

   y=-1/3x+4

2)  x=3y

    y=1/3x

The x variable represents the number of commercials and the yy variable represents the number of movies. Since the lines intersect at the point (6,2) we can say:

Emily's songs were played on 6 commercials and 2 movies.

​

 

4 0
1 year ago
Solve the equation y′ + 3y = t + e^(−2t).
Leni [432]
Hello,

I am going to remember:

y'+3y=0==>y=C*e^(-3t)

y'=C'*e^(-3t)-3C*e^(-3t)

y'+3y=C'*e^(-3t)-3Ce^(-3t)+3C*e^(-3t)=C'*e^(-3t) = t+e^(-2t)
==>C'=(t+e^(-2t))/e^(-3t)=t*e^(3t)+e^t
==>C=e^t+t*e^(3t) /3-e^(3t)/9

==>y= (e^t+t*e^(3t)/3-e^(3t)/9)*e^(-3t)+D
==>y=e^(-2t)+t/3-1/9+D
==>y=e^(-2t)+t/3+k


4 0
2 years ago
Mario builds a triangular table to fit in the corner of his rectangular bedroom. Is it possible to construct more than one table
Viefleur [7K]

Answer 1 with Explanation

Obtained from the question, Mario builds a triangular table to fit in a corner of the bedroom with the construction measure of 45,90 and 45 degrees which will be possible. In order to construct any physical object, proper tool are needed for accuracy of the object to built more than one of the similar table. With the help of proper instruments and measurement Mario can easily make a triangular table for his room's corner.

Answer 2 with Explanation

As Mario built the triangular table for the corner to fit his bedroom corner. He make use of the special instrument and tool for the measurement. Indeed, it is possible to construct more than one table with the angles 45,45,90 as each of them will be similar in shape but with different values of x, hence it will differ in sizes in terms of length. The length will differ as per the requirement of Mario's needs.

4 0
2 years ago
Darryl deposits $1,500 into a savings account that has a simple interest rate of 2.7%. Lori deposits $1,400 into a savings accou
igor_vitrenko [27]
Darryl:
Answer:
A = $1,905.00

(I = A - P = $405.00)

Equation:
A = P(1 + rt)

Lori:

Answer:
A = $1,932.00

(I = A - P = $532.00)

Equation:
A = P(1 + rt)

Thus $532-$405= $127 more in Lori's account
3 0
2 years ago
Read 2 more answers
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