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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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Maria is in the state park riding her bike on the new bike trail. She starts at the beginning of the trail and rides for 4 miles
Agata [3.3K]

Answer:

20 miles

Step-by-step explanation:

If Maria has been riding for 2 1/2 hours and Aiden only for 2. That means that the first 4 miles she rode alone was for 1/2 hour. So that is the rate.

1/2 hour for every 4 miles

Maria rode for 2 1/2 hours divided by 1/2 hours is 5. So 5 x 4mi = 20 miles

7 0
3 years ago
Read 2 more answers
giving brainliest and if u cant read down it says: if the spinner is spun 540 times throughout the day, how many dog or cat toys
Nataliya [291]

Answer:

324/540 cats and dogs should be expected to be given away

Step-by-step explanation:

First, write the fraction of the cats on the spinner plus the dogs on the spinner.

\frac{4}{10} + \frac{2}{10} = \frac{6}{10}

Now, we have to make the denominator 540 but we have to make it equal so you divide.

540 ÷ 10 = 54

So, our fraction should look like this.

\frac{x}{540}

Now, multiply 6 × 54 = 324

\frac{324}{540} is our answer

Have a great day!

6 0
3 years ago
What is the slope of the line that passes through the points (5,-5) and (5, - 7)?
anyanavicka [17]

Answer:

-2/0

Step-by-step explanation:

I am pretty sure this is called undefined.

8 0
3 years ago
Read 2 more answers
6 2/3 miles ➕ 4 11/16 =
mihalych1998 [28]

Answer:Add up fractions. The answer is 11 17/48

Step-by-step explanation:

hope this helps!

8 0
4 years ago
Read 2 more answers
If 24 is 60% of a value, what is the total value
yuradex [85]
The answer would be 40.
to answer this, u can use the is over of equals to % over hundred.
is        %
__ = ___
of     100
the is would be 24 and the percent would be 60.
so,
24     60
__ = ___
 x      100
to answer this u would cross multiply. 
24x100=2400
60x X=60x
then, divide
6\0x         2400
__\___ = _____
    6\0         60
2400 divided by 60 is 40.
40 is the answer.
7 0
3 years ago
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