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kifflom [539]
2 years ago
13

You place a cup of 200 degrees F coffee on a table in a room that is 67 degrees F, and 10 minutes later, it is 195 degrees F. Ap

proximately how long will it be before the coffee is 180 degrees F? Use Newton's law of cooling: T(t)=T[a]+(T[o]-T[a])e^-kt A. 40 minutes B. 15 minutes C. 1 hour D. 35 minutes
Mathematics
2 answers:
Marat540 [252]2 years ago
4 0
195=67+(200-67)e^(-10k)

195=67+133e^(-10k)

128=133e^(-10k)

128/133=e^(-10k)

ln(128/133)=-10k

k=-ln(128/133)/10

T(t)=67+133e^(tln(128/133)/10), if T(t)=180

180=67+133e^(tln(128/133)/10)

113=133e^(tln(128/133)/10)

113/133=e^(tln(128/133)/10)

ln(113/133)=tln(128/133)/10

10ln(113/133)=tln(128/133)

t=10ln(113/133)/ln(128/133)

t≈42.5 minutes...

t≈40 minutes (to nearest 5 minutes? :P)


tangare [24]2 years ago
3 0
43 mins to keep it
short but other than that same as the the other guy
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zavuch27 [327]

If I have a stack of pennies. And I have to tell that without counting whether there are even number of pennies or odd.

Even numbers are the numbers which are divisible by 2 and odd numbers are the numbers which are not divisible by 2.

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5 0
2 years ago
If Patricia drives at two-third of her usual speed, she covers a certain distance in one hour more than the time she takes while
zalisa [80]
Let r = usual driving rate
let t = usual driving time
We need to figure out t

The distance she covers in her usual time at her usual rate is r*t

The distance she covers in her new time at her new rate is:
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Set this equal to each other and solve for t.

rt = (2/3)r + (2/3)rt
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3 0
2 years ago
When the net is folded into the rectangular prism shown beside it, which letters will be on the front and back of the rectangula
earnstyle [38]
<h2>Answer:</h2>

<u>The correct option is </u><u>The letter on the front will be N. The letter on the back will be L. </u>

<h2>Step-by-step explanation:</h2>

When we fold the given net, we will get Q,P,M and N on sides. Side M will come to the top, side Q on the right side, side P on the left and side O on the bottom. The side which comes to the front will  be N of the observer and similarly the side L will come to the back of the rectangular prism.

4 0
2 years ago
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4 0
2 years ago
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The infield of a baseball field is a square
AnnZ [28]

Answer:

  106.1 ft/s

Step-by-step explanation:

You know the diagonal of a square is √2 times the length of one side, so the distance from 3rd to 1st is 90√2 feet ≈ 127.2792 ft.

The speed is the ratio of distance to time:

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_____

In case you have never figured or seen the computation of the diagonal of a square (the hypotenuse of an isosceles right triangle), consider the square with side lengths 1. The diagonal will cut the square into halves that are isosceles right triangles with leg lengths 1. Then the Pythagorean theorem can be used to find the diagonal length d:

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Since this is the diagonal for a side length of 1, any other side length will serve as a scale factor for this value. A square with a side length of 90 ft will have a diagonal measuring 90√2 ft.

7 0
2 years ago
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