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Evgen [1.6K]
3 years ago
7

The radioactive isotope 14C has a half-life of approximately 5715 years. A piece of ancient charcoal contains only 81% as much o

f the radioactive carbon as a piece of modern charcoal. How long ago was the tree burned to make the ancient charcoal
Mathematics
1 answer:
NikAS [45]3 years ago
5 0

Answer:

1758 years

Step-by-step explanation:

0.693/t1/2 = 2.303/t log No/N

t1/2 = half life of the C-14

t= time taken

No= amount of radioactive material originally present

N= amount of isotope after time t.

But N= 0.81 No

0.693/5715= 2.303/t log No/0.81No

0.00012 = 0.211/t

t =0.211 /0.00012

t= 1758 years

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A certain ore contains 21 percent gold. How much ore (in tons) is needed to obtain 882 tons of gold?
krok68 [10]

Answer:

it would be 4200 ore

Step-by-step explanation:

because 882/.21

6 0
2 years ago
a parabolic lamp is facing due east. The bulb (located at the focus) is 8 inches away from the vertex (located at the origin). t
True [87]

9514 1404 393

Answer:

  3 1/8 inches

Step-by-step explanation:

For focus-vertex distance p, the equation of the parabola can be written ...

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7 0
3 years ago
A bag contains 6 red and 10 black marbles. If Mia picks a marble, records its color, and returns it to the bag 200 times, how ma
Daniel [21]
She can expect to pick a black marble 125 times
7 0
3 years ago
NEED IT ASAP<br>Find the missing side. <br>3 is A^2 <br>5 is B^2<br><br>what is the missing side ​
nignag [31]

Answer:

5.83

Step-by-step explanation:

Use the Pythagorean theorem:

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4 0
3 years ago
Read 2 more answers
Find the slope of the line that passes through the pair of points (4.5, 13.5) and (–3.5, –9).
Zigmanuir [339]
Given two points: (x₁,y₁) and (x₂,y₂) the slope "m" will be:
m=(y₁-y₂) / (x₁-x₂)                or                  m=(y₂-y₁) / (x₂-x₁)

In this case:
(4.5 , 13.5)
(-3.5 , -9)

m=(-9-13.5) / (-3.5-4.5)=-22.5 / -8=2.8125

Answer: the slope will be m=2.8125.
3 0
3 years ago
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