About 92 days are taken for 90 % of the material to decay.
The mass of radioisotopes ([tex]m[/tex]), measured in milligrams, decreases exponentially in time ([tex]t[/tex]), measured in days. The model that represents such decrease is described below:
[tex]m(t) = m_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (1)
Where:
[tex]m_{o}[/tex] - Initial mass, in milligrams.[tex]m(t)[/tex] - Current mass, in milligrams.[tex]\tau[/tex] - Time constant, in days.In addition, the time constant is defined in terms of half-life ([tex]t_{1/2}[/tex]), in days:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex] (2)
If we know that [tex]m_{o} = 85\,mg[/tex], [tex]t_{1/2} = 27.7\,d[/tex] and [tex]m(t) = 8.5\,mg[/tex], then the time required for decaying is:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex]
[tex]\tau = \frac{27.7\,d}{\ln 2}[/tex]
[tex]\tau \approx 39.963\,d[/tex]
[tex]t = -\tau \cdot \ln \frac{m(t)}{m_{o}}[/tex]
[tex]t = -(39.963\,d)\cdot \ln \frac{8.5\,mg}{85\,mg}[/tex]
[tex]t\approx 92.018\,d[/tex]
About 92 days are taken for 90 % of the material to decay.
We kindly invite to check this question on half-life: https://brainly.com/question/24710827
A train goes at a constant speed. It can travel 150 miles in 2 1/2. How long will it take that train to travel 100 miles
Answer:
1 2/3 hours
Step-by-step explanation:
At constant speed, the time is proportional to the distance.
time/distance = 2.5 h/150 mi = x /100
x = 100(2.5/150) h = 5/3 h = 1 2/3 h
It will take the train 1 2/3 hours to travel 100 miles.
SOMEONE PLEASE BE FAST!!! Which pair of fractions and mixed numbers have a common denominator of 42?
Three and two-thirds and Five-sevenths
Two and one-sixth and Three-fourths
Five and three-fourteenths and One-fifth
One and four-sevenths and Five-eighths
Answer:
It's the first one. Why?
I converted all the mixed fraction into simplified form.
3 [tex]\frac{1}{3}[/tex] to [tex]\frac{11}{3}[/tex] + [tex]\frac{5}{7}[/tex]
I divided the denominator of 11/3 by 42. 42/3=14
and 5/7. 42/7, which is 6.
So I concluded the first answer was right because it didn't work out for the other variables.
I hope the answer was right, and I hope you have a great day luv. Bye!
find the values for k
5k^2 - 4k > 0
Answer:
[tex]5k^2-4k>0[/tex]
[tex]k(5k-4)>0[/tex]
In the image attached, you want the values above 0. Thus, the values of k would be in the red area, which is
[tex]k<0[/tex] or [tex]k>\frac{4}{5}[/tex]
Micah’s bill for dinner was $35.50. He left the server an 18% tip. How much money did Micah leave for the tip?Enter the correct answer in the box.
Answer:
$41.89
Step-by-step explanation:
100%=35.50
1%=0.3550
18%=6.39
$35.50+6.39=$41.89
Answer: 49.89 percent
Step-by-step explanation:
Be a good boy
Generate a frequency table for the following data: 3, 12, 25, 2, 3, 6, 17, 17, 15, 13, 20, 12, 21, 18, 19.
Use the ranges listed in the table:
Range Number of Values
1 – 5
6 – 10
11 – 15
16 – 20
21 – 25
What value should be placed in the second column for the range 11 – 15?
A: 4, B: 3, C: 5, D: 6
3
5
6
Answer:
4
Step-by-step explanation:
What is the slope of this line?
•5
•1/5
•-5
•-1/5
quick please
If 2 gallons of milk cost $8.00, how much is 1 quart of milk?
Michelle has $1200 in her savings account if the bank pays 3% interest per year on savings how much interest does she earn in a year? A: $360 b: $300 C: $30 D: $36
Answer:
d - $36
Step-by-step explanation:
I=Prt
(interest=principle*rate*time in years)
I=1200*.03*1
I=1200*.03
I=36
write the value of (2+root3)(2-root3)
Answer: 1
Step-by-step explanation: use foil and get 4-3.
In carbon dioxide molecules, for every 2 oxygen
atoms there is 1 carbon atom. How many oxygen atoms
combine with 50 carbon atoms to form carbon dioxide
molecules?
Answer:
100 oxygen molecules simple math
Please help ME for brainliest.
Answer:
Equation: -1.2y-4.2y=-3.78
Solved: y=0.7
Step-by-step explanation:
-1.2y-4.2y=-3.78
-5.4y=-3.78
y=0.7
I will take you up on your brainliest offer
4g as a verbal expression
Answer:
Step-by-step explanation:
1) A number g multiplied by 4
2) Product of 4 and g
3) 4 times g
Be quiet! The teacher (be) angry
what is this how so i do this
identify the types of each triangle
Answer:
Step-by-step explanation:
1. right angled (isosceles)
2. acute (equilateral or equiangular)
3. obtuse
5. acute
Answer:
Triangle number one is a right triangle. Triangle two is an equilateral triangle. Triangle three which is below triangle one is an obtuse triangle. The fourth triangle is an acute triangle.
Step-by-step explanation:
One is a right triangle because it has one right angle.
Two is an equilateral triangle because all of the three angles are 60 degrees.
Three is an obtuse triangle because one of the three angles is more than 90 degrees.
Finally, 4 is an acute triangle because all of the three angles are less than 90 degrees
An Uber ride costs a flat rate to start the ride and then charges an additional amount per mile. By the 3rd mile, the total cost of the trip is $9. By the 7th mile, the total cost is $17. What is the flat rate that Uber charges and how much does it cost per mile?
Step-by-step explanation:
the function is
ride cost c = mile rate r × miles m + flat rate f
c = r×m + f
now let's put the values in we know and solve for r and f :
9 = r×3 + f
17 = r×7 + f
now, since one term is the same in both equations, we use a simple trick for speed, and we subtract the whole first equation from the second :
17 = r×7 + f
- 9 = r×3 + f
-------------------
8 = r×4 + 0
r = 8/4 = $2
9 = 2×3 + f = 6 + f
f = $3
the first rate is $3, and it costs $2 per mile.
How many cubic blocks of side length
inch would it take to fill a
rectangular prism with a length,
width, and height of inch,
inch, and inch, respectively?
Answer: inch cubic blocks
Step-by-step explanation:
Enrollment in mathematics courses
increased from 1440 students last
semester to 1925 students this semester.
Find the percent increase, to the nearest
whole percent
Answer:
25%
Step-by-step explanation:
1925 - 1440 = 485
X/100 = 485/1925 (what percent is 485 of 1925) (%/100=is/of)
(485 x 100) / 1925 (cross multiply)
48500/1925 = 25%
A cab company charges a $3 boarding rate in addition to its meter which is $2 for every mile. What is the equation?
Please give an actual answer
It costs $12 to enter the fair and $0.50 per ticket for rides. How much total would you spend if you paid admission and bought 70 tickets? plz hurry will mark brainlest
The initial cost is $12 to enter.
Each ticket is $.50
we want to find out how much it costs for 70 tickets so we multiply the cost by the amount;
70 x .50 = 35
Therefor including the entry fee, it would cost $35 + $12
Which is $47
I hope this helps! :)
Answer number 4 this is due tomorrow
Answer:
The next mark should be at (3,-3)
SUPER EASY DO FAST PLEASEE
is that a japanese symbol for beginner
suppose 40% of college students plan to vote in the election. now suppose we randomly select 200 college students and ask them if they plan to vote. what is the probability that more than 75 of the 200 students sampled plan to vote?
Answer:
62.5%
Step-by-step explanation:
Sara took skydiving lessons. The Skydome charges $45 per hour for lessons. Sara also
gave her Skydiving Instructor a tip of $20.
(a) Define the unknown in the scenario and assign it a letter or symbol.
What are the 3 primary ways to migrate client data to QuickBooks Online
Answer:
Use the Import Data tool. Use the Export Data tool. Enter data manually into the QuickBooks Online forms and check registers. Use the Attachments tool
1A. Tính:
a) ( -14) + 5 + 17 + 14 b) 40 +13 + ( -25) + ( -13)
c) ( -5) + ( -146)+ ( -15) + 14 d) ( -2) + (-5) + 20 + (- 13)
Answer:
7868
Step-by-step explanation:
i don’t get the question which makes it harder for me to answer
Answer:
See below:
Step-by-step explanation:
As there doesn't appear to be a full question, I guess you want me to tell you the definition of complementary.
Complementary and Supplementary angles are when angles make up 90 degrees or 180 degrees respectively, the order being:
+ Supplementary Angles are angles that add up to 180 degrees
+ Complementary Angles are angles that add up to 90 degrees.
So in this context, it means that the sum of the degrees of angles 9 and 10 are equal to 90 degrees.
Cheers!
please help thank you
k(-3)=36(2)
hope it helps
what percentage of this grid is shaded
how many more squares need to be shaded so that 60% of the grid is shaded?
Answer:
44%, and 4
Step-by-step explanation:
The grid has 5 rows and 5 columns so we have 5*5 = 25 squares.
25 squares represent 100 % of the grid
a) In the grid 11 of the 25 total squares are blue, so if
25 squares are 100%
11 squares will be x%
x= (11* 100) / 25 = 1100/ 25 = 44 %
b) we find the number of squares that gives us 60 %
25 squares are 100%
x squares will be 60%
x= (60*25)/ 100 = 15
The question is " How many more squares " so we have to compare with the 11 given ones in part a)
15 -11 = 4
4 more squares will give 60 % blue grid.
0.314 x 100 = help me pls
Answer:
your answer would be 31.4 :)
Step-by-step explanation:
pls answer quick.
which problem-solving strategy would be best to solve this problem how many different ways can you give change for 45 cents?
A) make a table, chart or list
B) work backwards
C) use a formula
D) look for a pattern
Answer:
a:make a table ,chart or list