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olchik [2.2K]
3 years ago
5

Question 5: How long will it take for 2 g of a sample of iodine-131, which has a half-life of about 8 days, to decay to 0.04 g?

Mathematics
1 answer:
Aleonysh [2.5K]3 years ago
4 0

This problem can be represented through the following equation

A = A₀(1/2)^t/h

where

A----------->  is the amount of substance left after time t

A₀ ----------> is the original amount---------> 2 g

h------------->  is the half-life-----------> 8 days

for A=0.04 g

t=?

0.04 = 2(1/2)^t/8

0.02 = (1/2)^t/8

Take ln on both sides:

ln(0.02) = ln [(1/2)^t/8]

ln(0.02) = (t/8)(ln 1/2)

t = 8*ln(0.02)/ln(1/2)

t = 45.15 days

the answer is 45.15 days

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What is the equation of the line, in standard form, that passes through (4, -3) and is parallel to the line whose equation is 4x
Serggg [28]

Answer:

The equation of this line would be 4x + y = 13

Step-by-step explanation:

In order to find this equation we must first find the slope of the original line. To do this, we solve the original equation for y.

4x + y - 2 = 0

4x + y = 2

y = -4x + 2

The original slope (the coefficient of x) is -4, which means the new slope will also be -4 because parallel lines have the same slope. Now, we can use this slope along with the point in point-slope form to find the equation of the line. Just plug in the numbers and solve for the coefficient.

y - y1 = m(x - x1)

y + 3 = -4(x - 4)

y + 3 = -4x + 16

4x + y + 3 = 16

4x + y = 13

4 0
3 years ago
If arc AD = 62° and arc BC = 28°, then what is the measure of angle AED?
nata0808 [166]
Well according to the Inscribed Angle Theorem, the angle inscribed in a circle is equal to one-half of its intercepted arc. We can apply that theorem to this problem as well. So the measure of AED = 1/2( arc AD + arc BC). Plug in the numbers and simplify.
AED = 1/2( 62 + 28)
AED = 1/2( 90 )
AED = 45
So the measure of angle AED is B. 45 degrees.
Hope I helped!
6 0
3 years ago
Help me!! need help!!!!! 10 minutes due!
Aleks04 [339]

Answer:

3

Step-by-step explanation:

The slope is 3 because the equation is y=mx+b. If you add in the terms m=3 and b=0. It is y=3x. M is the slope, so the slope is 3!

6 0
3 years ago
Read 2 more answers
Please help!!!! I don’t get this
Stella [2.4K]
The trig function sine, often abbreviated as "sin" (pronounced the same way as "sine"), is essentially the ratio or fraction of the opposite side and the hypotenuse. See the attached image for a reference.

The leg opposite angle B is side AC. Note how B is not present in the sequence "AC". Visually, we are as far away as possible from point B. This side is 16 units long. So AC = 16

The hypotenuse is the longest side of the right triangle. Always always always. This longest side is opposite the largest angle (90 degrees). Therefore the hypotenuse is BC = 17.46

In summary so far, we have,
opposite side = AC = 16
hypotenuse BC = 17.46

Let's use those values to compute sin(B)

sin(Angle) = opposite/hypotenuse
sin(B) = AC/BC
sin(B) = 16/17.46
sin(B) = 0.916 (this is approximate)
sin(B) = 0.92 (rounding to nearest hundredth)

This points to the final answer of choice A) 0.92

--------------------------------

Edit: Sorry nearly forgot about the reference image. I attached it just now.

4 0
3 years ago
From the intersection for the following sets.
zaharov [31]
Since x is intersecting y, it will be XnY =(0, 10)
3 0
3 years ago
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