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3 years ago

3. Ann wants to paste 18 posters on her bedroom wall. She wants to put the same

Mathematics

1 answer:

nekit [7.7K]3 years ago

3 0

Answer:

Step-by-step explanation:

18÷2=9

So, Ann could have 9 rows of posters with 2 posters in each row.

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Initially 100 milligrams of a radioactive substance was present. After 6 hours the mass had decreased by 3%. If the rate of deca

Hitman42 [59]

Answer:

The half-life of the radioactive substance is 135.9 hours.

Step-by-step explanation:

The rate of decay is proportional to the amount of the substance present at time t

This means that the amount of the substance can be modeled by the following differential equation:

$\frac{dQ}{dt} = -rt$

Which has the following solution:

$Q(t) = Q(0)e^{-rt}$

In which Q(t) is the amount after t hours, Q(0) is the initial amount and r is the decay rate.

After 6 hours the mass had decreased by 3%.

This means that $Q(6) = (1-0.03)Q(0) = 0.97Q(0)$ . We use this to find r.

$Q(t) = Q(0)e^{-rt}$

$0.97Q(0) = Q(0)e^{-6r}$

$e^{-6r} = 0.97$

$\ln{e^{-6r}} = \ln{0.97}$

$-6r = \ln{0.97}$

$r = -\frac{\ln{0.97}}{6}$

$r = 0.0051$

$Q(t) = Q(0)e^{-0.0051t}$

Determine the half-life of the radioactive substance.

This is t for which Q(t) = 0.5Q(0). So

$Q(t) = Q(0)e^{-0.0051t}$

$0.5Q(0) = Q(0)e^{-0.0051t}$

$e^{-0.0051t} = 0.5$

$\ln{e^{-0.0051t}} = \ln{0.5}$

$-0.0051t = \ln{0.5}$

$t = -\frac{\ln{0.5}}{0.0051}$

$t = 135.9$

The half-life of the radioactive substance is 135.9 hours.

6 0

3 years ago

87+56=____<br> (f r e e p o i n t s)<br> prolly gonna give brainliest

pogonyaev

Answer: 143

Step-by-step explanation:

Thanks for the free points

5 0

3 years ago

1.44 x 106<br> In standard form

Lorico [155]

Answer: The way you would write this in standerd form would be like this one point fourty four times one hundered six. Let me know if this correct or not.

Step-by-step explanation:

3 0

3 years ago

What is 8v+w+7-8v+2w simplified

lys-0071 [83]

What's 8v+w+7-8v+2w simplified?
Your answer is 3w+7.

8 0

4 years ago

Read 2 more answers

0/3 x 11 > 11 , whats the empty 0?

Cloud [144]

Answer:

This inequalitie is wrong because 0 is not more than 11

Step-by-step explanation:

8 0

3 years ago