Question 1 ( point) A 64g sample of Germanium-66 is left undisturbed for 12.5 hours. At the end of that period, only 2.0g remain. How many half-lives transpired during this time period? half-lives Answer = Blank 1:
Answer:
2.5 half-lives
Step-by-step explanation:
Find [tex]t_{h}[/tex] in [tex]N(t)=N_{0}e^{-kt}[/tex] given [tex]N(t) = 2, N_{0} =64,t=\frac{25}{2}[/tex]
[tex]N(t)[/tex] is the amount after the time [tex]t[/tex], [tex]N_0[/tex] `is the initial amount, [tex]t_{h}[/tex] is the half-life
We know that after half-life there will be twice less the initial quantity:
[tex]N(t_{h})=\frac{N_{0} }{2}=N_{0}e^{kt_{h} }[/tex].
Simplifying gives [tex]\frac{1}{2} =e^{-kt_h} or k = -\frac{In(\frac{1}{2}) }{t_{h} } .[/tex]
Plugging this into the initial equation, we obtain that [tex]N(t)=N_{0}e^\frac{In(\frac{1}{2}) }{t_{h} }[/tex]or [tex]N(t)= N_{0} (\frac{1}{2})^\frac{t}{t_h}.[/tex]
Finally, just plug in the given values and find the unknown one.
From [tex]2=64(\frac{1}{2})^\frac{\frac{25}{2} }{t_h}[/tex], we have that [tex]t_h[/tex] = [tex]\frac{25 In (2)}{2 In (32)\\}[/tex]
So you should get: [tex]t_{h} =\frac{25 In (2)}{2 In (32)\\}=2.5.[/tex]
MARK ME AS BRAINLIEST IF YOU WISHThe number of half-lives that transpired during this time period is equal to 2.5 hours.
Given the following data:
Time = 12.5 hours.
Initial mass = 64 grams.
Remaining mass = 2.0 grams.
How to determine the number of half-lives.Mathematically, the amount of a radiocative element that is remaining after time (t-hours) is given by this formula:
[tex]ln(\frac{A}{A_0} )=ln(\frac{1}{2} )\frac{t}{H}[/tex]
Where:
A is the amount remaining.Ao is the initial amount.H is the half-life.t is the time.Substituting the given parameters into the formula, we have;
ln(2/64) = ln(1/2) × 12.5/H
-3.466 = -0.693 × 12.5/H
H = 12.5 × -0.693/-3.466
H = 12.5 × 0.1999
H = 2.5 hours.
Read more on half-life here: https://brainly.com/question/25750315
reasons why students fail exams
Factorise
1) 9a^2 - 6a
Answer:
[tex]3a(3a - 2)[/tex]
Step-by-step explanation:
[tex]3(3a ^{2} - 2a) \\a(3a - 2) [/tex]
A basket contains four apples and six peaches. You randomly select one piece of fruit and eat it. Then you randomly select another piece of fruit. What is the probability that both pieces of fruit are apples.
Answer:
Answer as a fraction: 4/15
Answer as a decimal: 0.267
The decimal version is approximate rounded to three decimal places.
Step-by-step explanation:
6 apples, 4 peaches
6+4 = 10 pieces of fruit total
The probability of picking an apple is 6/10 = 3/5
After you pick and eat the apple, there are 10-1 = 9 pieces of fruit left. Also, the probability of picking a peach is 4/9, as there are 4 peaches out of 9 fruit left over.
Multiply out 3/5 and 4/9 to get (3/5)*(4/9) = (3*4)/(5*9) = 12/45 = 4/15
Using a calculator, 4/15 = 0.267 approximately.
I NEED HELP ASAP!!<3
Graph the following piecewise function.
helppppppp pleaseeee
Answer:
A
Step-by-step explanation:
2.5 x 3.4 = 8.5
A square painting has a side length of 13 inches.
What is the area of the painting?
The area of the painting is
square inches.
Answer:
Step-⚫️_by-step explanation:
If the area of a circle is 50.25 meters what is the radius
Answer:
≈3.99938
Step-by-step explanation:
The side lengths of four triangles are listed below. Determine whether each triangle is a right triangle Choose Yes or No for each set of side lengths.
a. 4,5,6 Yes No
b. 5, 12, 13 Yes No
C. 8, 15, 17 Yes No
d. 10, 15, 20 Yes No
Answer:
yes, yes, no, no
Step-by-step explanation:
The sum of a number and six times its reciprocal is 10. Find the number
Answer:
two solutions work: x = 5 + [tex]\sqrt{19}[/tex] and x = 5 - [tex]\sqrt{19}[/tex]
Step-by-step explanation:
x + 6 ( 1/x ) = 10
x^2 + 6 = 10x
x^2 - 10x + 6 = 0
x = 5 + [tex]\sqrt{19}[/tex], 5 - [tex]\sqrt{19}[/tex]
1. According to New Jersey Transit, the 8:00 a.m. weekday train from Princeton to New York
City has a 90% chance of arriving on time on a randomly selected day. Suppose this claim is
true. Suppose 6 days are chosen at random. Let X = the number of days on which the train
arrives on time.
(B) Find the mean of X. Interpret this value in context. SHOW YOUR WORK.
1 inch x 3/4 inch x 1/2 inch
Answer:
3/8
Step-by-step explanation:
Find the length of arc AD. Use 3.14 for .
Round to the nearest tenth.
7.9 cm
B
66.4
C
[ ? ]cm
Enter
Answer:
Length of arc AD = 15.7 cm
Step-by-step explanation:
Length of arc = [tex]\frac{\theta}{360}(2\pi r)[/tex]
Here, θ = Central angle subtended by the arc
r = radius of the circle
From the picture attached,
Central angle subtended by arc AD = 360° - (180° + 66.4°)
= 113.6°
Length of arc AD = [tex]\frac{(113.6)}{360}(2\pi )(7.9)[/tex]
= [tex]\frac{113.6}{360}(2)(3.14)(7.9)[/tex]
= 15.655 cm
≈ 15.7 cm
Length of arc AD = 15.7 cm
Answer:
12.4
Step-by-step explanation:
Just did it.
what shape can be formed from the following net
Answer:
square pyramid
Step-by-step explanation:
Answer:
star
Step-by-step explanation:
The results of a national survey showed that on average, adults sleep 6.3 hours per night. Suppose that the standard deviation is 1.6 hours. (a) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 3.1 and 9.5 hours. % (b) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 2.3 and 10.3 hours. % (c) Assume that the number of hours of sleep follows a bell-shaped distribution. Use the empirical rule to calculate the percentage of individuals who sleep between 3.1 and 9.5 hours per day. % How does this result compare to the value that you obtained using Chebyshev's theorem in part (a)
Answer:
a) 75%.
b) 84%
c) Within 2 standard deviations from the mean is 95%. The normal distribution has a higher percentage of observations closer to the mean than a non normal distribution, so this percentage is larger.
Step-by-step explanation:
Empirical Rule:
The Empirical Rule states that, for a normally distributed random variable:
Approximately 68% of the measures are within 1 standard deviation of the mean.
Approximately 95% of the measures are within 2 standard deviations of the mean.
Approximately 99.7% of the measures are within 3 standard deviations of the mean.
Chebyshev Theorem:
The Chebyshev Theorem can also be applied to non-normal distribution. It states that:
At least 75% of the measures are within 2 standard deviations of the mean.
At least 89% of the measures are within 3 standard deviations of the mean.
An in general terms, the percentage of measures within k standard deviations of the mean is given by [tex]100(1 - \frac{1}{k^{2}})[/tex].
In this question:
Mean: 6.3 hours
Standard deviation: 1.6 hours
(a) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 3.1 and 9.5 hours.
3.1 = 6.3 - 2*1.6
9.5 = 6.3 + 2*1.6
Within 2 standard deviations, so the minimum percentage is 75%.
(b) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 2.3 and 10.3 hours.
How many standard deviations from the mean?
One standard deviation is 1.6
These measures are 10.3 = 6.3 = 6.3 - 2.3 = 4. This is k standard deviations, in which
[tex]k = \frac{4}{1.6} = 2.5[/tex]
The minimum percentage is:
[tex]100(1 - \frac{1}{k^{2}}) - 100(1 - \frac{1}{2.5^{2}}) = 84%[/tex]
So 84%.
(c) Assume that the number of hours of sleep follows a bell-shaped distribution. Use the empirical rule to calculate the percentage of individuals who sleep between 3.1 and 9.5 hours per day.
Within 2 standard deviations from the mean is 95%. The normal distribution has a higher percentage of observations closer to the mean than a non normal distribution, so this percentage is larger.
Is this right? Help?
Answer:
That is wrong bc it says quotient and quotient means a division sign which i dont see on your answer,
Step-by-step explanation:
The correct answer should be...
3/2x
Im srry if wrong (and the "/" means division)
A right rectangular prism has a length of 6 centimeters, a width of 7 centimeters, and a height of 5 centimeters.
What is the volume of the prism?
____cm3
a) 214
b) 197
c) 210
CORRECT ANSWER= BRAINLY!!
Answer: c is the answer
Step-by-step explanation: the formuals for volume is length x width x height, 6x7x5, which is 210
Answer: C
Step-by-step explanation: Easy, just do length x width x height(l x w h). So, 6x7x5 = 210
what is the value of the 1 in 56.123
Answer:
The value of 1 is tens =) i hope i help u
A bakery sold 210 vanilla cupcakes in a day, which was 42% of the total number of cupcakes sold that day. How many total cupcakes did the bakery sell that day?
PLEASE DONT SAY RANDOM ANSWERS ILL GIVE 15 POINTS
Answer:
88.2 is your answer.
Answer:500
Step-by-step explanation:on delta math
what's the fourth proportional of 0.2, 0.5, 6
Answer:
15
Step-by-step explanation:
a:b::c:d
a/b=c/d .......(eq 1)
let a=0.2, b=0.5, c=6, d=x
Not put values in eq 1
0.2/0.5 = 6/a
By cross multiplication we get:
0.2xa = 6x0.5
0.2a = 3
Dividing by 0.2 on both sides we get
0.2a/0.2 = 3/0.2
a = 15
Therefore The fourth proportional is 15
7. Find the inverse of f(x) = -2x + 10. Please show work.
Answer- y = - x/2 + 5
Step by step - Replace f (x) with y.
Y = - 2x + 10
Interchange the variables.
x= -2y + 10
Solve for y.
Y= x/2 +5
PLEASE HELP!!!!!! ILL GIVE BRAINLIEST *EXTRA 40 POINTS** !! DONT SKIP :((
Answer:
yes
Step-by-step explanation:
2 + 16(1) = 18
2+16 = 18
2(2) + 11(1) = 15
4+11=15
... Helppppp!! will mark brainiest
Answer: The answer is C
Step-by-step explanation:
C is the answer because the base is +2 and the coefficent is 1/2 which is rise over run so you go up one space and to the right two spaces.
Write 237 m as a fraction of 3.5 km
Answer:
0.237/3.5
Step-by-step explanation:
In order to rite 237 m as a fraction of 3.5 km, 237m must be in the same unit as 3.5km
it is necessary to convert, 237m to km
1000m = 1 km
so 237m = 237/1000= 0.237
0.237/3.5
Please I need help it’s an emergency
Answer:
the answer is 36
Step-by-step explanation:
beacuse if we use the pythagorean theorem for 9 and 12 we get 15 which means that the perimeter is P=9+15+12=36
How many digits will be in the quotient?
39) 4,641
1 digit
3 digits
2 digits
4 digits
Challenger elementary school has 800 students every Wednesday 12% of the students stay after school for the chess club. How many students attend the chess club on wednesdays?
Answer:
96 people
Step-by-step explanation:
i used a calculator
Jillian and her friend went shopping. They were both looking for some new CD's. Jillian went to Music Matrix and spent $25.56 on 4 CD's. Her friend
spent $18.45 on 3 CD's. Who got the better deal? Show your work for each person. Answer who got the better deal and explain your reasoning,
Answer:
Her friend got the better deal.
Step-by-step explanation:
For Jillians equation look at
$22.56/4 = $6.39 per CD
For her friends equation look at
$18.45/3 = $6.15 per CD
Jillian's friend got the better deal because she paid less per CD as shown in the equations above.
50 apples cost $25. How much would 75 apples cost?
Answer:
37.5
Step-by-step explanation:
If 50 apples cost 25 then all you need to do is 25 x 1.5 = 37.5
And we know this is correct because 25 divided by 2 is 12.5.
so 12.5 is how much for 25 apples and if you multiply 25 times 3 it is equal to 75 so you need to mutliply 12.5 times 3.
12.5 x 3 = 37.5
PLEASE HELP ITS DONE IN 16 HOURSSS!!!
question: A substance with 12 negatively charged atoms combined with a substance that has 10 positively charge atoms. What is the total charge of the substance when the atoms are combined?
answer options:
+22
-22
+2
-2