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3 years ago

Iodine-125 has a half-life of about 60 days.

Mathematics

1 answer:

Murljashka [212]3 years ago

3 0

62.5 mg sample will remain after 240 days

Step-by-step explanation:

Given

Half-life = T = 60 days

The formula for calculating the quantity after n half lives is given by:

$N = N_0(\frac{1}{2})^n$

Here

N is the final amount

N_0 is the initial amount

n is the number of half lives passed

The number of half lives are calculated by dividing the time for which the remaining quantity has to be found by half life

The quantity has to be calculated for 240 days so,

$n = \frac{240}{60}\\n = 4$

Given

$N_0 = 1000\ mg$

Putting the values in the formula

$N = 1000 (\frac{1}{2})^4\\=1000 * \frac{1}{16}\\=\frac{1000}{16}\\=62.5\ mg$

Hence,

62.5 mg sample will remain after 240 days

Keywords: Half-life, sample

Learn more about half-life at:

#LearnwithBrainly

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Which equation represents a line that is perpendicular to the line whose equation is -2y=3x+7

notsponge [240]

Answer:

Any line with the slope of 2/3 would be perpendicular.

Step-by-step explanation:

To find this, first solve the equation for y.

-2y = 3x + 7

y = -3/2x - 7/2

Perpendicular lines always have opposite and reciprocal slopes. Therefore, we flip the slope in the original equation (-3/2 becomes -2/3) and then we change the sign (-2/3 becomes 2/3)

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3 years ago

Write the differential equation model that fits the given description. (a) The rate of change of the volume of a snowball (due t

miskamm [114]

Answer:

a) he rate of change of the volume of a snowball (due to melting) is proportional to the square of the volume at time t. Initially, the snowball has a volume of 900 cm3

$\frac{dV(t)}{dT} = A*V(t)^{2} \\$ and V(0) = 900 $cm^{3}$

where A is a real constant, it appears because it says that the change i volume (dV/dt) is "proportional" to $V(t)^{2}$ . Furthermore, we should assume that A is a negative number, because the volume of the snowball will decrease as the time pasese by.

(b) For an insect moving along some path, the velocity at time t is proportional to the square root of its position.

$\frac{dr(t)}{dt} = B*\sqrt{r(t)}$

Here again appears a constant B for the "proportional" part. And i wrote the velocity as $\frac{dr(t)}{dt}$ "the rate of change of the position with respect to te time".

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3 years ago

2. Kim is x years old. Jordan is 7 years older than Kim. Four times Jordan’s age is equal to 200. (a) Write an equation that cou

wlad13 [49]

(a) Kim x years old
Jordan x+7 years old
4(x+7)=200
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x=43
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3 years ago

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quester [9]

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3 years ago

if a motercycle is moving at a constant speed down the highway of 40 km/hr, how long would it the motorcycle to travel 10 km

ahrayia [7]

Answer:

15 minutes

Step-by-step explanation:

First, the motorcycle goes at a speed of 40 km/hr.

The question asks for how long it would take to travel 10 km.

Well, there are 60 minutes in an hour, since we will be translating into minutes.

Also, 10 km is 1/4 of 40 km, so it would make sense that the time length would be 1/4 of an hour as well.

1/4 of 60 minutes is 15 minutes. So it takes 15 minutes for the motorcycle to travel 10 km.

Now, if all this wordy stuff is too much to comprehend, you can also solve using proportional relationships.

$\frac{40km}{60min}=\frac{10km}{xmin}$

Now cross multiply:

$40km*xmin=10km*60min\\40x=600$

Divide both sides by 40:

$\frac{40x}{40}=\frac{600}{40}\\x=15$

Again, this shows that it wouls take 15 minutes for the motorcycle to travel 10 km.

6 0

3 years ago