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4 years ago

A 20mg sample of thorium-233 decays to 17mg after 5 min. determine the half life of thorium-233?

1 answer:

3 0

Let r be the decay rate (time in minutes) 17 = 20 e^(5r) 0.85 = e^(5r) ln 0.85 = 5r similarly, ln 0.5 = hr ... where h is the half-life, so dividing the 2 equations, ln 0.85 / ln 0.50 = 5r / hr = 5/h h = 5 ln 0.50 / ln 0.85 h = 21.3 min b) 1/20 = 0.05, so ln 0.85 = 5r ln 0.05 = tr t = 5 ln 0.05 / ln 0.85 t = 92.2 min

You might be interested in

1 + 1 express as fraction

lana66690 [7]

Answer: 2 over 1

Step-by-step explanation:

1+1=2

However we want this as a fraction

Any whole number as a fraction is just over one

Therefore the final answer is 2 over 1

You’re welcome Kaeya!

3 0

2 years ago

Read 2 more answers

2/3 x − 9 − 2x + 2 = 1 Which is an equivalent equation after combining like terms?

Kaylis [27]

Answer:

Any equation shown in the explanation

Step-by-step explanation:

Hello!

Combining like terms means combining terms with the same variables.

So combing all x's, all y's, all numbers, etc.

2/3x - 9 - 2x + 2 = 1

combine the x's

-1 1/3 x - 9 + 2 = 1

combine normal numbers

-1 1/3 x - 7 = 1

Add 7 to both sides

-1 1/3x = 8

Make mixed number into improper fraction

-4/3x = 8

Multiply both sides by 3

-4x = 24

Divide both sides by -4

x = -6

The answer would be any of the equation I showed above

Hope this helps!

8 0

4 years ago

In triangle JKL, m of angle J = 90, m of angle K = 30, and m of angle L = 60. Which of the following statements about triangle J

Jobisdone [24]

Answer:

# Answer B is true ⇒ KL = 2(JL)

# Answer C is true ⇒ JK = √3(JL)

# Answer F is true ⇒ JK = √3/2(KL)

Step-by-step explanation:

* Lets explain the ratio between the sides of the triangle

- In Δ JKL

∵ The measure of angle J is 90°

∴ KL is the hypotenuse

∵ The measure of angle K is 30°

∴ JL is the opposite side to angle 30°

∵ The measure of angle L is 60°

∴ JK is the opposite side to the angle 60°

- There is a fact in the triangle which has angles 30° , 60° , 90°

# The length of the side opposite to the angle of measure 30° is

half the length of the hypotenuse

∵ KL is the hypotenuse

∵ JL is the opposite side to the angle of measure 30°

∴ JL = 1/2 KL OR KL = 2 JL

# The length of the side opposite to the angle of measure 60° is

√3 the length of the opposite side to the angle 30°

∵ JK is the opposite side to the angle of measure 60°

∵ JL is the opposite side to the angle of measure 30°

∴ JK = √3 JL

# The length of the side opposite to the angle of measure 60° is also

half √3 the length of the hypotenuse

∵ JK is the opposite side to the angle of measure 60°

∵ KL is the hypotenuse

∴ JK = √3/2 KL

- From the relation above

# Answer B is true ⇒ KL = 2(JL)

# Answer C is true ⇒ JK = √3(JL)

# Answer F is true ⇒ JK = √3/2(KL)

6 0

4 years ago

Ojinska sold many more raffle tickets when she told people they had a 10 percent chance of winning a prize than when she told th

Mumz [18]

Answer: C. framing

Step-by-step explanation:

People tends to decides on options based on the type of framing presented to them. Framing effect is a cognitive bias where people decide on options presented to them based on whether it's presented with positive or negative connotations and remarks. In the case above, the reaction of people to the same idea when presented positively and negatively was different. It implies that the framing of the same idea may influence people's decision

3 0

3 years ago

40 points I'll mark you as BRAINLIEST for the person with the right answers .

Karo-lina-s [1.5K]

9. y=-1/4x^2+4x-19
group
y=(-1/4x^2+4x)-19
undistribute -1/4
y=-1/4(x^2-16x)-19
take 1/2 of -16 and squer it to get 64 then add neg and pos inside
y=-1/4(x^2-16x+64-64)-19
factorperfect square
y=-1/4((x-8)^2-64)-19
expand
y=-1/4(x-8)^2+16-19
y=-1/4(x-8)^2-3
vertex is (8,-3)

10.
group
y=(1/4x^2-3x)+18
undistribute
y=1/4(x^2-12x)+18
take 1/2 of -12 and square it and add neg and pos isndie
y=1/4(x^2-12x+36-36)+18
factor
y=1/4((x-6)^2-36)+18
expand
y=1/4(x-6)^2-9+18
y=1/4(x-6)^2+9
get to form (x-h)^2=4p(y-k)
minus 9 both sides and times 4
(x-6)^2=4(y-9)
(x-6)^2=4(1)(y-9)
so 1>0 so opens up and focus is 1 above vertex
vertex is (6,9)
so focus i (6,10)

11.
y=(-1/6x^2+7x)-80
y=(-1/6)(x^2-42x)-80
take 1/2 of linear coefient and squer it and add negative and positive inside
-42/2=-21, (-21)^2=441
y=(-1/6)(x^2-42+441-441)-80
factor perfect square the square
y=(-1/6)((x-21)^2-411)-80
expand
y=(-1/6)(x-21)^2+73.5-80
y=(-1/6)(x-21)^2-6.5
add 6.5 to both sid
y+6.5=(-1/6)(x-21)^2
times both sides by -6
-6(y+6.5)=(x-21)^2
(x-21)^2=-6(y+6.5)
(y-21)^2=4(-3/2)(y-(-6.5))
vertex is
-3/2<0 so directix is above
it is -3/2 or 1.5 units above the vertex
up is y so
-6.5+1.5=-5
the directix is y=-5

11.
in form (y-1)^2=4p(x+3)
opens left or right
(y-1)^2=4(4)(x+3)
vertex is (-3,1)
4>0 so opens right
dirextix is to left
it is 4 units to left
(-3,1)
left right is x
4 left of -3 is -4-3=7
x=-7 is da directix

3 0

3 years ago