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3 years ago

Find the probability of answering the first three multiple choice questions correctly

Mathematics

1 answer:

alisha [4.7K]3 years ago

4 0

1/12 if each Question is A-D

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4x-5y+2z=-3<br> 6x+4y+9z=8<br> 11x-2y-z=7

Nutka1998 [239]

Answer:

thank you i need that

Step-by-step explanation:

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3 years ago

How do I find the values of x and y?

zepelin [54]

All 3 angles =180...

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3 years ago

Suppose after 2500 years an initial amount of 1000 grams of a radioactive substance has decayed to 75 grams. What is the half-li

krok68 [10]

Answer:

The correct answer is:

Between 600 and 700 years (B)

Step-by-step explanation:

At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:

$A(t) = A_0 e^{(kt)}\\where:\\A(t) = Amount\ left\ at\ time\ (t) = 75\ grams\\A_0 = initial\ amount = 1000\ grams\\k = decay\ constant\\t = time\ of\ decay = 2500\ years$

First, let us calculate the decay constant (k)

$75 = 1000 e^{(k2500)}\\dividing\ both\ sides\ by\ 1000\\0.075 = e^{(2500k)}\\taking\ natural\ logarithm\ of\ both\ sides\\In 0.075 = In (e^{2500k})\\In 0.075 = 2500k\\k = \frac{In0.075}{2500}\\ k = \frac{-2.5903}{2500} \\k = - 0.001036$

Next, let us calculate the half-life as follows:

$\frac{1}{2} A_0 = A_0 e^{(-0.001036t)}\\Dividing\ both\ sides\ by\ A_0\\ \frac{1}{2} = e^{-0.001036t}\\taking\ natural\ logarithm\ of\ both\ sides\\In(0.5) = In (e^{-0.001036t})\\-0.6931 = -0.001036t\\t = \frac{-0.6931}{-0.001036} \\t = 669.02 years\\\therefore t\frac{1}{2} \approx 669\ years$

Therefore the half-life is between 600 and 700 years

5 0

3 years ago

Jovie is maintaining a camp fire. She has kept the fire steadily burning for 101010 hours with 151515 logs. She wants to know ho

Eva8 [605]

Answer:666 hours

Step-by-step explanation: The reason is that if you turn the problem into an equation it would be h=Lx. h= hours. L=how long the log lasts and x=how many logs. So when you plug in the numbers you get 101010=L*151515. So we need to find L. What you do is you divide both sides by 151515 since it is the opposite of multiplication. 151515/151515 gets crossed out and 101010/151515 is .6666666666666 irrational. So the equation now looks like .666666 irrational=L. So .66666 irrational is your L. Know you plug .666666 irrational into your original equation. Which is now h=.6666 irrational*x. So to find how long the fire keeps on burning with 999 logs you just plug 999 into x and now your equation looks like this h=.6666 irrational*999. If you multiply .6666 irrational by 999 your final answer is 666.

8 0

3 years ago

Add brackets to make this statement correct.. 12 - 2 x 3 + 1 = 4

Talja [164]

Answer:

$12 - (2 \times 3) + 1 = 4$

3 0

2 years ago

Read 2 more answers