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postnew [5]
2 years ago
10

How much of a radioactive substance must be presented to decay to 80 grams in 12 years if the half-life of the substance is 7.6

years?
Mathematics
2 answers:
elena-s [515]2 years ago
8 0

Answer:

239 grams.

Step-by-step explanation:

Half life t(1/2) = ln 2 / k

So 7.6 = ln 2 / k

k = ln 2 / 7.6 = 0 0901204

N = No e^-kt

So after 12 years

80 = No / e^(-0.0901204*12)

No = 80 / e^(-0.0901204*12)

= 239.

max2010maxim [7]2 years ago
4 0

Answer:

Radioactive in half life is 51gram

Step-by-step explanation:

80grams:12years

X :7.6years

12x÷x=x

7.6×80÷12=51gram

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The circumference of a circular painting is 59.66 feet. What is the radius of the painting? Use 3.14 for π and do not round your
Studentka2010 [4]

Answer:

9.5 feet

Step-by-step explanation:

So let's review the equations we need to know.

Circumference= π x d or π x 2r

Since we are solving for r, let's stick with the 2nd one.

Next, plug in the values.

59.66=3.14 x 2r

simplify.

59.66=6.28r

9.5=r

done!

the radius is 9.5 feet!

3 0
3 years ago
Need help with b, picture attached.
Vikki [24]
7500/75=100
This means that a field of those dimensions would not be the required length of a minimum of 110 feet. 
7 0
3 years ago
Please, I need help I'm way behind.
gregori [183]

Answer:

\frac{18√2}{√3}

Step-by-step explanation:

  1. The lengths of the sides of a 30-60-90 triangle are in the ratio 1:2:√3.
  2. The lengths of the sides of a 45-45-90 triangle are in the ratio 1 : 1 : √2
  3. We can get the length of the longest side of the bottom triangle is 9×2÷√3 = \frac{18}{√3}
  4. And based on the theory shown on the 2nd step, we can get x (the length of the longest side of the upper triangle) is \frac{18}{√3}x√2  
3 0
4 years ago
-5–(-6)<br> Show work pls Nd simplify
zubka84 [21]

Answer:

Step-by-step explanation:

Here you go mate

Step 1

-5-(-6)  Equation/Question

Step 2

-5-(-6)  Simplify

5-6

Step 3

5-6  Subtract them

Answer

1

Hope this helps

7 0
3 years ago
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The lengths of three sides of a triangle are 10 centimeters, 11 centimeters, and 13 centimeters. Find the measure of the smalles
SashulF [63]

Answer:

  • 48.4°

Step-by-step explanation:

The smallest angle is opposite to the smallest side.

<u>Use the law of cosines to find the angle opposite to side with the length of 10 cm:</u>

  • cos A = (b² + c² - a²)/(2bc)
  • cos x = (11² + 13² - 10²)/(2*11*13)
  • cos x = 190/286
  • cos x = 0.664 (rounded)
  • x = arccos (0.664)
  • x = 48.4° (rounded)
5 0
2 years ago
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