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3 years ago

15

The CD Warehouse is having a clearance sale. A CD player that originally sells for $60 is now priced at $36. What is the percent

decrease in the price?

1 answer:

WINSTONCH [101]3 years ago

3 0

Answer: 24

Step-by-step explanation:

i did the problem and got it right

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A roast turkey is taken from an oven when its temperature has reached 185 degrees F and is placed on a table in a room where the

Vedmedyk [2.9K]

(a) Using Newton's Law of Cooling, $\dfrac{dT}{dt} = k(T - T_s)$ , we have $\dfrac{dT}{dt} = k(T - 75)$ where T is temperature after T minutes.
Separate by dividing both sides by T - 75 to get $\dfrac{dT}{T - 75} = k dt$ . Integrate both sides to get $\ln|T - 75| = kt + C$ .

Since $T(0) = 185$ , we solve for C:
$|185 - 75| = k(0) + C\ \Rightarrow\ C = \ln 110$
So we get $\ln|T - 75| = kt + \ln 110$ . Use T(30) = 150 to solve for k:
$\ln| 150 - 75 | = 30k + \ln 110\ \Rightarrow\ \ln 75 - \ln 110= 30k \Rightarrow \\ k= \frac{1}{30}\ln (75/110) = \frac{1}{30}\ln(15/22)$

So

$\ln|T - 75| = kt + \ln 110 \Rightarrow |T - 75| = e^{kt + \ln110} \Rightarrow \\ \\
|T - 75| = 110e^{kt} \Rightarrow T - 75 = \pm110e^{(1/30)\ln(15/22)t} \Rightarrow \\
T = 75 \pm110e^{(1/30)\ln(15/22)t}$

But choose Positive because T > 75. Temp of turkey can't go under.

$T(t) = 75 + 110e^{(1/30)\ln(15/22)t} \\
T(45) = 75 + 110e^{(1/30)\ln(15/22)(45)} = 136.929 \approx 137{}^{\circ}F$

(b)

$T(t) = 75 + 110e^{(1/30)\ln(15/22)t} = 75 + 110(15/22)^{t/30} \\
100 = 75 + 110(15/22)^{t/30} \\
25 = 110(15/22)^{t/30} 
\frac{25}{110} = (15/22)^{t/30} \\
\ln(25/110) / ln(15/22) = t/30 \\
t = 30\ln(25/110) / ln(15/22) \approx 116\ \mathrm{min}$

Dogs of the AMS.

4 0

3 years ago

A paint mixture was formed by mixing exactly 3 colors of paint. By volume, the mixture was x% blue paint, y% green paint, and z%

sergeinik [125]

Answer:

Both statements are sufficient to answer the question

Step-by-step explanation:

Given:

- The paint mixture has following proportions:

Total volume of paint = T

Blue: x*T / 100

Green: y*T/100

Red: z*T/100

Find:

Statement 1: x = y

Statement: z = 60

Which of the above statement is sufficient to calculate the amount of green paint used

Solution:

Statement 1:

- The amount of blue paint used is:

1 gallon = x*T / 100

- x = y,

1 gallon = y*T / 100

Hence,

Amount of green paint used is 1 gallon

- The statement is sufficient

Statement 2:

- The amount of red paint used is:

3 gallon = z*T / 100

T = 300 / z = 300 / 60 = 5 gallons

T = R + B + G

G = T - R - B

G = 5 - 3 - 1

G = 1 gallons

Hence,

Amount of green paint used is 1 gallon

- The statement is sufficient

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3 years ago

An online data base charges $25 an hour during the day and $12.50 an hour at night. If a research company paid $250 for 12 hours

Firdavs [7]

Answer

Find out the which system of equations could be used to determine the number of hours charged at the day rate (d) and at the night rate (n) .

To proof

As given in the question

Let us assume that the number of hours charged at the day rate = d

Let us assume that the number of hours charged at the night rate = n

An online data base charges $25 an hour during the day and $12.50 an hour at night. If a research company paid $250 for 12 hours of use.

Total working hour in a company including day and night be 12 hours .

than the equation become in the form

d + n = 12

also

An online data base charges $25 an hour during the day

$12.50 an hour at night.

If a research company paid $250 for 12 hours of use.

than the equation becomes

25d + 12.50n = 250

than the two equation are

d + n = 12 , 25d + 12.50n = 250

multiply first by 25 and subtracted from 25d + 12.50n = 250

25d - 25d + 12.50n - 25n = 250 - 300

12.5 n = 50

$n = \frac{50}{12.5}$

n = 4hours

put this in the d + n = 12

d + 4 =12

d = 12-4

d = 8 hours

Therefore the number of hours charged at the day rate is 8 hours and at the night rate is 4hours .

Hence proved

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3 years ago

The table and the graph each show a different relationship between the same two variables, x and y:

SCORPION-xisa [38]

When x=2 y = 110 which means when when x=1 y = 55
the graph would be 11*55 or 605
The table would be 280/4= 70 70*11=770
Which means the difference is 770-605=165

165 is ur answer

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3 years ago

NOT TRYING TO RUSH YOU OR ANYTHING BUT CAN YOU PLEASE HURRY UP AND HELP ME!!

Nadya [2.5K]

Answer: A.

Step-by-step explanation:

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3 years ago

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