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Step2247 [10]
3 years ago
10

You have 480 grams of a radioactive kind of samarium. If its half-life is 90 years,

Mathematics
1 answer:
lisov135 [29]3 years ago
3 0

Answer:

120 grams will be left after 180 years.

Step-by-step explanation:

A radioactive half-life refers to the amount of time it takes for half of the original isotope to decay and its given by

                                             N(t)=N_0(\frac{1}{2})^\frac{t}{t_{1/2}}

where,

N(t) = quantity of the substance remaining

N_0 = initial quantity of the substance

t = time elapsed

t_{1/2} = half life of the substance

From the information given we know that:

  • The initial quantity is 480 g,
  • The half-life is 90 years,
  • 180 years is the time elapsed.

And we want to find how much will be left. For this we use the above formula.

N(t)=480\left(\frac{1}{2}\right)^{\frac{180}{90}}\\\\N(t)=480\left(\frac{1}{2}\right)^2\\\\N(t)=480\cdot \frac{1}{2^2}=120

120 grams will be left after 180 years.

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A theater has 60 seats on the front row. There are seven additional seats in each following row.
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Answer:

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Step-by-step explanation:

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Third row=67+7=74

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To get rhe number of seats in any row x then let y be the number of seats in row x

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(b)

Using the above formula

y(x)=53+7(x)

Replace x with 18 hence

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