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3 years ago

Picture and info down below!

Mathematics

1 answer:

eimsori [14]3 years ago

8 0

The formula for perimeter is 2L + 2W and the formula for the area is L * W, since we don't know the width we will divide 35:7 = 5 and he the measurement for the width.

Now just add L + W = 12 and multiply by 2 the answer is 24
Or 2 * 7 + 2 * 5 = 24

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Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

Aleonysh [2.5K]

Answer:

t=5.18 minute

Step-by-step explanation:

Using Newton's law of cooling

$\frac{dT}{dt}=-k(T-T_{s})$

T is temperature of a cup of coffee at any time t $T_{s}$ , is the temperature of the surrounding and k is a constant of proportionality in this negative because temperature is decreasing.

$T(0)=190\\T(1)=170\\T_{s}=66$

$\frac{dT}{dt}=-k(T-T_{s})\\\frac{dT}{(T-T_{s})}=-k*dt\\\int\limits {\frac{1}{T-T_{s} } } \, dT=-\int\limits {k} \, dt\\ln(T-T_{s})=k*t+C\\e*ln(T-T_{s})=e^{k*t+C} \\T-T_{s}=e^{k*t}*e^{C}\\e^{C}=C\\T-T_{s}=e^{k*t}*C\\T=T_{s}+e^{k*t}*C$

To find constant knowing the time and the temperature the first step of the change of energy in cup of coffee

$T=T_{s} +e^{-k*t}*C\\ C=190-66=124\\170=66+124*e^{-k*2}\\ 170-66=124*e^{-k*2}\\ln(\frac{104}{124})=ln*e^{-k*2}\\-0.175=-k*2\\k=0.08794$

Now using the constant of decreasing can find the time to be a 145 temperature the cup of coffee

$145=66+124*e^{-k*t} \\145-66=124*^{-0.087*t}$

$ln(0.637)=ln*e(-0.087*t)\\-0.45=-0.087*t\\t=5.18minutes$

4 0

3 years ago

Can someone give me the answers for these?

Alinara [238K]

I think the first one is ( C :3 ) and the other one is B 2

5 0

3 years ago

PLEASE PLEASE PLEASE HELP ME. IM STUCK IN A SUMMER SCHOOL AND IF I DONT GET GOOD GRADES ILL GET IN BIG TROUBLE AND IM TOTALLY LO

Mrrafil [7]

Answer:

We know that in the box there are:

4 twix

3 kit-kat

Then the total number of candy in the box is:

4 +3 = 7

Here we want to find the probability that we draw two twix.

All the candy has the same probability of being drawn from the box.

So, the probability of getting a twix in the first drawn, is equal to the quotient between the number of twix and the total number of candy in the box, this is:

p = 4/7

Now for the second draw, we do the same, but because we have already drawn one twix before, now the number of twix in the box is 3, and the total number of candy in the box is 6.

this time the probability is:

q = 3/6 = 1/2

The joint probability is the product of the individual probabilities, so here we have

P = p*q = (4/7)*(1/2) = 2/7

b) same reasoning than in the previous case:

For the first bar, the probability is:

p = 3/7

for the second bar, the probability is:

q = 2/6 = 1/3

The joint probability is:

P = p*q = (3/7)*(1/3) = 1/7

c) Suppose that first we draw a twix.

The probability we already know that is:

p = 4/7

Now we want another type, so we need to draw a kit-kat, the probability will be equal to the quotient between the remaining kit-kat bars (3) and the total number of candy in the box (6)

q = 3/6

The joint probability is:

P = p*q = (4/7)*(3/6) = 2/7

But, we also have the case where we first draw a kit-kat and after a twix, so we have a permutation of two, then the probability in this case is:

Probability = 2*P = 2*2/7 = 4/7

3 0

3 years ago

Which of the following numbers is irrational?

andrew-mc [135]

Answer:

Step-by-step explanation: always remember that sign as irrational

7 0

3 years ago

About 33% of people who get their feet examined are found to have an ingrown toenail. What is the probability of a podiatrist ex

enot [183]

Answer:

The correct answer is 0.94147

Step-by-step explanation:

Let A denote the event that the podiatrist finds the first person with an ingrown toenail.

And (1 - A) denote the event that the podiatrist does not find the ingrown toenail.

While examining seven people, the podiatrist can find the very first person to have an ingrown toenail. Similarly he can find the second patient to have the ingrown toenail. Going in this way the probability of the first person to have an ingrown toenail is given by:

= A + (1 - A) × A + (1 - A) × (1 - A) × A + (1 - A) × (1 - A) × (1 - A) × A + (1 - A) × (1 - A) × (1 - A) × (1 - A) × A + (1 - A) × (1 - A) × (1 - A) × (1 - A) × (1 - A) × A + (1 - A) × (1 - A) × (1 - A) × (1 - A) × (1 - A) × (1 - A) × A.

= $\frac{1}{3} + \frac{2}{3} \frac{1}{3} + \frac{2}{3} \frac{2}{3} \frac{1}{3} + \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{1}{3} + \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{1}{3} + \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{1}{3} + \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{2}{3} \frac{1}{3} .$

= $\frac{1}{3} + \frac{2}{3} \frac{1}{3} + (\frac{2}{3}) ^{2} \frac{1}{3} + (\frac{2}{3})^{3} \frac{1}{3} + (\frac{2}{3})^{4} \frac{1}{3} + (\frac{2}{3})^{5} \frac{1}{3} + (\frac{2}{3})^{6} \frac{1}{3}.$

= 0.94147

We can also solve the above expression by using the geometric progression formula as well where common ratio is given by $\dfrac{2}{3}$ .

8 0

3 years ago