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ICE Princess25 [194]
3 years ago
11

Calculate the unit rate: 63 sit-ups in 3 1/2 minutes

Mathematics
1 answer:
mestny [16]3 years ago
7 0

18, you do 63/3.5 to get how many for 1 minute

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Find x please and FAST!!!
Vsevolod [243]

Answer:

19

Step-by-step explanation:

Angle ZYW is congruent to angle YWX, so the 3 angles must add to 180.

(3x - 5) + 90 + 2x = 180

5x + 85 = 180

5x = 95

x = 19

4 0
2 years ago
I need the result of 14?2?7?3?9=10
PilotLPTM [1.2K]

Answer: yes

Step-by-step explanation:

7 0
3 years ago
Two different radioactive isotopes decay to 10% of their respective original amounts. Isotope A does this in 33 days, while isot
Andrews [41]

Answer:

The approximate difference in the half-lives of the isotopes is 66 days.

Step-by-step explanation:

The decay of an isotope is represented by the following differential equation:

\frac{dm}{dt} = -\frac{t}{\tau}

Where:

m - Current mass of the isotope, measured in kilograms.

t - Time, measured in days.

\tau - Time constant, measured in days.

The solution of the differential equation is:

m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }

Where m_{o} is the initial mass of the isotope, measure in kilograms.

Now, the time constant is cleared:

\ln \frac{m(t)}{m_{o}} = -\frac{t}{\tau}

\tau = -\frac{t}{\ln \frac{m(t)}{m_{o}} }

The half-life of a isotope (t_{1/2}) as a function of time constant is:

t_{1/2} = \tau \cdot \ln2

t_{1/2} = -\left(\frac{t}{\ln\frac{m(t)}{m_{o}} }\right) \cdot \ln 2

The half-life difference between isotope B and isotope A is:

\Delta t_{1/2} = \left| -\left(\frac{t_{A}}{\ln \frac{m_{A}(t)}{m_{o,A}} } \right)\cdot \ln 2+\left(\frac{t_{B}}{\ln \frac{m_{B}(t)}{m_{o,B}} } \right)\cdot \ln 2\right|

If \frac{m_{A}(t)}{m_{o,A}} = \frac{m_{B}(t)}{m_{o,B}} = 0.9, t_{A} = 33\,days and t_{B} = 43\,days, the difference in the half-lives of the isotopes is:

\Delta t_{1/2} = \left|-\left(\frac{33\,days}{\ln 0.90} \right)\cdot \ln 2 + \left(\frac{43\,days}{\ln 0.90} \right)\cdot \ln 2\right|

\Delta t_{1/2} \approx 65.788\,days

The approximate difference in the half-lives of the isotopes is 66 days.

4 0
3 years ago
Read 2 more answers
Simplify the expression. <br> -3(b – 7)
pychu [463]
-3(b - 7)

Distributive property

-3*b = -3b

-3*7 = -21

-3b + 21

Answer:  -3b + 21

6 0
3 years ago
(Please answer! You will get brainliest, and over 100+ points..)
irakobra [83]

11 quarters and 18 dimes

Hope this helps! :D

8 0
3 years ago
Read 2 more answers
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