1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Stels [109]
3 years ago
12

A radioactive substance decays exponentially: The mass at time t is m(t) = m(0)e^kt, where m(0) is the initial mass and k is a n

egative constant. The mean life M of an atom in the substance is
[infinity]
M = âk â« te^kt dt.
0

For the radioactive carbon isotope, 14C, used in radiocarbon dating, the value of k is -0.000121. Find the mean life of a 14C atom.
Mathematics
1 answer:
forsale [732]3 years ago
5 0

Answer:

mean life = 8264.5 s

Step-by-step explanation:

k = - 0.000121

The relation is given by

m = mo e^{kt}

Now, the mean life is the life time for which the sample retains.

The mean life is the reciprocal of the decay constant.  

The relation between the mean life and the decay constant is

\tau =\frac{1}{k}\\\\\tau = \frac{1}{0.000121} = 8264.5 seconds

You might be interested in
Which problem is represented by this inequality 12x≥48
MArishka [77]
What are the answers choices
8 0
3 years ago
If X denotes the number of heads in n tosses of a coin, what is the standard deviation of the random variable X? Does this stand
vfiekz [6]

Answer:

\sigma=\sqrt{np(1-p)}=\sqrt{n*0.5(1-0.5)}=\frac{\sqrt{n}}{2}

As we can see the deviation is proportional to the value of n and if n increase then the deviation increases too. So then the deviation would be larger when n gets larger.

Step-by-step explanation:

Previous concepts

The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".

The probability mass function for the Binomial distribution is given as:  

P(X)=(nCx)(p)^x (1-p)^{n-x}  

Where (nCx) means combinatory and it's given by this formula:  

nCx=\frac{n!}{(n-x)! x!}  

Solution to the problem

We can define the following random variable X ="Number of heads in n tosses of a coin".

We assume that the coin is fair and then P(H)= 0.5 for any trial so then we can model X with the following distribution:

X \sim Bin (n, p=0.5)

For this distribution the mean and variance are given by:

E(X)=np=n*0.5=\frac{n}{2}

Var(X)= np(1-p) = n*0.5*(1-0.5) = 0.25 n = \frac{n}{4}

And the deviation would be just the square root of the variance and we got:

\sigma=\sqrt{np(1-p)}=\sqrt{n*0.5(1-0.5)}=\frac{\sqrt{n}}{2}

Does this standard deviation get larger or smaller when n gets larger?

As we can see the deviation is proportional to the value of n and if n increase then the deviation increases too. So then the deviation would be larger when n gets larger.

3 0
3 years ago
What is 10 less than x
Degger [83]
10 less than 'x' may be represented algebraically as the quantity (x - 10) .

There's no way to calculate its numerical value without knowing the value of 'x'.
8 0
4 years ago
Read 2 more answers
A typical airplane flies at an altitude of 38,000 feet. Part A: Write an integer to represent an airplane's altitude.
irga5000 [103]

Answer:

+ 38,000

Step-by-step explanation:

Given that:

Altitude of airplane = 38,000

The altitude of an object such as airplane in this scenario refers to the height of the airplane above sea level. The sea level is represented as a zero point (mid level) such that distance below are negative and those above are positive.

Hence, at an altitude of 38000 feets, altitude of airplane can be represented as +38,000 feets.

6 0
3 years ago
Evaluate 5 - (4 + 2)2<br> O A. 9<br> O B. -15<br> O C. 5<br> O D.-31
solong [7]

Answer:

exponents first then multiply and subtract after

Step-by-step explanation:

the answer is 5

8 0
3 years ago
Other questions:
  • Which of the inequalities represents the statement, "two times a number x, less 15, is greater than or equal to 4 times the numb
    6·2 answers
  • Help me!! With this until question fifteen thank you
    13·1 answer
  • What is the percent of change from 56 to 22? round to the nearest percent
    5·1 answer
  • hey how do i solve this problem i’m clueless and don’t know how to do it. if you can could you explain it please?
    6·1 answer
  • Choose the definition for the function. <br> Please help me!!!
    11·1 answer
  • Which state had a population hundreds four thousand one hundred ninety-four
    9·2 answers
  • Can anyone help with 6
    6·2 answers
  • What is the constant of variation k of the line y=kx through (5,8)
    9·2 answers
  • Writing to explain: Badal has 120 cm3 of water. He wants to pour it into a rectangular vase that is 4 cm high, 4 cm wide, and 5
    15·2 answers
  • A parallelogram has an area of 323 square meters and a base of 17 meters. What is the height?
    9·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!