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3 years ago

Erica spent $115 on school she actually spent $82.50 what is Erica's percent of error

Mathematics

2 answers:

MaRussiya [10]3 years ago

7 0

I think it is 32.5% but I could be wrong

9966 [12]3 years ago

7 0

About thirty-nine percent

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A storage tank contains a liquid radioactive element with a half-life of 96 years. It will be relatively safe for the contents t

PolarNik [594]

Answer:

The tank must remain intact for 1183 years.

Step-by-step explanation:

Exponential equation for decay:

The amount of a substance after t years is given by:

$A(t) = A(0)e^{rt}$

In which A(0) is the initial amount and r is the decay rate.

A storage tank contains a liquid radioactive element with a half-life of 96 years.

This means that $A(96) = 0.5A(0)$ , and we use this to find r.

$A(t) = A(0)e^{rt}$

$0.5A(0) = A(0)e^{96r}$

$e^{96r} = 0.5$

$\ln{e^{96r}} = \ln{0.5}$

$96r = \ln{0.5}$

$r = \frac{\ln{0.5}}{96}$

$r = -0.0072$

$A(t) = A(0)e^{-0.0072t}$

It will be relatively safe for the contents to leak from the tank when 0.02% of the radioactive element remains. How long must the tank remain intact for this storage procedure to be safe?

This is t for which $A(t) = 0.0002A(0)$ . So

$A(t) = A(0)e^{-0.0072t}$

$0.0002A(0) = A(0)e^{-0.0072t}$

$e^{-0.0072t} = 0.0002$

$\ln{e^{-0.0072t}} = \ln{0.0002}$

$-0.0072t = \ln{0.0002}$

$t = -\frac{\ln{0.0002}}{0.0072}$

$t = 1183$

The tank must remain intact for 1183 years.

5 0

2 years ago

The number of cubic feet of water in a curved container can be approximated by v = 0.95h2.9. use a calculator to find the amount

Sati [7]

The first thing we must do for this case is to rewrite the expression of the volume correctly.
We have then:
v = 0.95 * h ^ 2.9
Substituting the value of h we have:
v = 0.95 * (7.5) ^ 2.9
v = 327.6432831
round to the nearest tenth:
v = 327.6 feet ^ 3
Answer:
the amount of water in the container when h = 7.5 feet is:
v = 327.6 feet ^ 3

3 0

2 years ago

The result of subtracting (4x2 − x) from -3x2 is .

abruzzese [7]

Answer:

Step-by-step explanation:

-7x/\2+x

3 0

2 years ago

Read 2 more answers

Problem is attached, please show steps

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