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Delvig [45]
3 years ago
8

If 3.0 grams of strontium-90 in a rock sample remained in 1989, approximately how many grams of strontium-90 were present in the

original rock sample in 1933?
Mathematics
1 answer:
kirill [66]3 years ago
5 0

Answer:

<em>11.29 grams </em><em>of strontium-90 were present in the original rock sample in 1933.</em>

Step-by-step explanation:

Strontium has a half-life of 28.8 years. Therefore,

1989 - 1933 = 56 years.

56 / 28.8 = 1.94 half-lives

Thus, the quantity of the radioisotope remaining will double for each half-life elapsed. moving backwards in time.

Therefore, moving backwards in time by 1.94 half-lives, the quantity remaining will double by 1.94 times.

Thus, the amount remaining in 1933 is

3.0 × (1.94)² = <em>11.29 grams</em>

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Zielflug [23.3K]

Answer:

Step-by-step explanation:

In this system we have the force of the spring and the gravitational force. The equation that describes that is

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7 0
3 years ago
Read 2 more answers
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ladessa [460]

Answer:

$8.75

Step-by-step explanation:

To calculate this you could use two methods. The first method is to find out what 10% is and multiply it by 5. The second method is to calculate 50% using the formula.

<u>Method 1:</u>

To work this out you would simply divide 17.50 by 10, which is 1.75. This is because percentages are out of 100 and so by dividing by 10 we are finding out what 10% is. Then you would multiply 1.75 by 5, which is 8.75. Then you would minus 8.75 from 17.50, which is 8.75.

<u></u>

1) Divide 17.50 by 10.

17.50/10=1.75

2) Multiply 1.75 by 5.

1.75*5=8.75

3) Minus 8.75 from 17.50.

17.50-8.75=8.75

4) The new price is $8.75

<u>Method 2:</u>

<u></u>

The formula for percentages is.

\frac{percentage}{100} * amount

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To work this out you would first divide 50 by 100, which gives you 0.5. Then you would multiply 0.5 by 17.50, which is 8.75. Then you would minus 8.75 from 17.50, which is 8.75.

1) Divide 50 by 100.

50/100=0.5

2) Multiply 0.5 by 17.50.

17.50*0.5=8.75

3) Minus 8.75 from 17.50.

17.50-8.75=8.75

4) The new price is $8.75.

7 0
2 years ago
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JulsSmile [24]

Answer:

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Step-by-step explanation:

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3 years ago
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Answer:

Step-by-step explanation:

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4 0
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Factorise the following:<br><img src="https://tex.z-dn.net/?f=%7B3x%7D%5E%7B2%7D%20%20%2B%205x%20-%2012" id="TexFormula1" title=
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Answer:

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Step-by-step explanation:

Given

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= (x + 3)(3x - 4)

Thus

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6 0
2 years ago
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