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3 years ago

Answer please brainliest

Mathematics

2 answers:

tangare [24]3 years ago

7 0

Answer:

$45$

Step-by-step explanation:

$45\% \\ = \frac{45}{100} \\ = 0.45$

hope this helps

brainliest appreciated

good luck! have a nice day!

Firlakuza [10]3 years ago

4 0

Answer:

Step-by-step explanation:

45% = 0.45

45/100 = 0.45

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I need help please it would mean alot

Bezzdna [24]

Answer:

C i just got it right

Step-by-step explanation:

7 0

3 years ago

The half-life of cesium-137 is 30 years. Suppose we have a 180-mg sample. (a) Find the mass that remains after t years. (b) How

DedPeter [7]

Answer:

a) $Q(t) = 180e^{-0.023t}$

b) 11.4mg of cesium-137 remains after 120 years.

c) 225.8 years.

Step-by-step explanation:

The following equation is used to calculate the amount of cesium-137:

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

In which Q(t) is the amount after t years, Q(0) is the initial amount, and r is the rate at which the amount decreses.

(a) Find the mass that remains after t years.

The half-life of cesium-137 is 30 years.

This means that Q(30) = 0.5Q(0). We apply this information to the equation to find the value of r.

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

$0.5Q(0) = Q(0)e^{-30r}$

$e^{-30r} = 0.5$

Applying ln to both sides of the equality.

$\ln{e^{-30r}} = \ln{0.5}$

$-30r = \ln{0.5}$

$r = \frac{\ln{0.5}}{-30}$

$r = 0.023$

$Q(t) = Q(0)e^{-0.023t}$

180-mg sample, so Q(0) = 180

$Q(t) = 180e^{-0.023t}$

(b) How much of the sample remains after 120 years?

This is Q(120).

$Q(t) = 180e^{-0.023t}$

$Q(120) = 180e^{-0.023*120}$

$Q(120) = 11.4$

11.4mg of cesium-137 remains after 120 years.

(c) After how long will only 1 mg remain?

This is t when Q(t) = 1. So

$Q(t) = 180e^{-0.023t}$

$1 = 180e^{-0.023t}$

$e^{-0.023t} = \frac{1}{180}$

$e^{-0.023t} = 0.00556$

Applying ln to both sides

$\ln{e^{-0.023t}} = \ln{0.00556}$

$-0.023t = \ln{0.00556}$

$t = \frac{\ln{0.00556}}{-0.023}$

$t = 225.8$

225.8 years.

8 0

3 years ago

Read 2 more answers

(+18)(-25)(-10)(+2) porfavor

erastovalidia [21]

Answer:

9,000 but Idk if that plus is indicating adding or if it is indicating positive

7 0

3 years ago

A used car salesperson makes 5% of her sales in commission. Last week, she sold used cars worth a total of $120,000.

meriva

So what you first need to do is get your 5% into a decimal. To do that just move the decimal to the left 2 times. 5%—> .05
After that you multiply 120,000 with .05
120,000x.05= 6,000
And the answer is that she got $6,000 for commission.

8 0

3 years ago

Read 2 more answers

An equation is shown. 21t = 252

alexdok [17]

Answer:

t = 12

Step-by-step explanation:

<em>252 divded by 21 =</em>

<em /> $12$ '

8 0

3 years ago