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adelina 88 [10]
3 years ago
5

Maggie was doing research for her Ph.D. in physics when a 12 mg sample of radioactive material decayed to 3 mg in 26 minutes. De

termine the half life of this substance.
Mathematics
1 answer:
netineya [11]3 years ago
3 0

The general way to work this out is to solve the general expression for
the remaining quantity versus half-life, using logarithms.  But that's not
necessary with these numbers.

Look at the numbers:

-- 3 mg is  1/4  of  12 mg.

-- 1/4  is the product of  (1/2) x (1/2).

-- So the  3 mg is what's left of  12 mg after  2  half-lives.
The  26  minutes must be two half-lives.

-- The half-life of that substance is  26/2 = <em>13 minutes</em>.

Go Maggie !

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Answer:

The original length was 41 inches and the original width was 16 inches

Step-by-step explanation:

Let

x ----> the original length of the piece of​ metal

y ----> the original width of the piece of​ metal

we know that

When squares with sides 5 in long are cut from the four corners and the flaps are folded upward to form an open box

The dimensions of the box are

L=(x-10)\ in\\W=(y-10)\ in\\H=5\ in

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V=930\ in^3

so

930=(x-10)(y-10)5

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186=(x-10)(y-10) -----> equation A

Remember that

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186=(y+25-10)(y-10)

solve for y

186=(y+15)(y-10)\\186=y^2-10y+15y-150\\y^2+5y-336=0

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see the attached figure

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