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
lord [1]
3 years ago
11

Plutonium–238 has a yearly decay constant of 7.9 × 10-3. If an original sample has a mass of 15 grams, how long will it take to

decay to 12 grams?
(At = A0e-kt)
Mathematics
1 answer:
eduard3 years ago
8 0
The answer is 28 years

At = A0 * e^(-k * t)
At = 12 g
A0 = 15 g
k = 7.9 × 10^-3 = 0.0079 
t = ?

12 = 15 * e^(-0.0079 * t)
12/15 = e^(-0.0079 * t)
0.8 = e^(-0.0079 * t)

Logarithm both sides (because ln(e) = 1:
ln(0.8) = ln(e^(-0.0079 * t))
ln(0.8) = (-0.0079 * t) * ln(e)
-0.223 = -0.0079 * t
t = -0.223 / -0.0079
t = 28.23
t ≈ 28 years
You might be interested in
A rocket is launched from a tower. The height of the rocket, y in feet, is related to the
stiv31 [10]

Answer:

8.67 seconds.

Step-by-step explanation:

I hope this helps!

3 0
3 years ago
Giving brainily if ur correct
frozen [14]

the answer is 60.

all you have to do is multiply all the numbers.

3 × 4 × 5 = 60

first:

multiply two of the numbers together. anything you like.

4 × 3 is 12

and now multiply the left number with the

result.

which is

5 × 12 = 60

8 0
3 years ago
Read 2 more answers
What is the measure of m? m=? 24 6
Vitek1552 [10]

Answer:

Follow the steps

Step-by-step explanation:

Angle M is 95 degrees.

3 0
3 years ago
Seven times the difference of a number and 1
weeeeeb [17]
Describe that better
8 0
3 years ago
Read 2 more answers
If a student randomly guesses at 20 multiple-choice questions, find the probability that the student gets exactly four correct.
ad-work [718]

Answer:

Probability = 0.190

Step-by-step explanation:

Given:

Number of questions, 'n' = 20

Each question has four choices.

Let event of choosing correct answer be success and its probability be represented by 'p'.

Therefore, event of choosing wrong answer is failure and its probability be represented by 'q'.

Now, probability of success is choosing one correct answer out of 4 options. So, p=\frac{1}{4}=0.25

Now, 'p' and 'q' are complements of each other. Therefore,

q=1-p=1-0.25=0.75

Now, we need 4 successes. Therefore, x=4

Using Bernoulli's theorem to find 'x' successes from 'n' questions, we get:

P(x)=_{x}^{n}\textrm{C}p^xq^{n-x}

Plug in 4 for 'x', 20 for 'n', 0.25 for 'p' and 0.75 for 'q'. Solve.

P(4)=_{4}^{20}\textrm{C}(0.25)^4(0.75)^{20-4}\\P(4)=_{4}^{20}\textrm{C}(0.25)^4(0.75)^{16}\\P(4)=4845\times (0.25)^4\times (0.65)^{16}\\\\P(4)=0.1896\approx0.190

Therefore, the probability of getting 4 correct answers out of 20 questions is 0.190.

6 0
3 years ago
Other questions:
  • Explain the difference between a line with zero slope and a line with an undefined slope
    7·2 answers
  • Which equation is equivalent to 2x+5y=-2?
    7·2 answers
  • X+23x+61°<br> What kind of pair is it
    12·1 answer
  • F(x) = 5 - 3x, find (-1)<br><br> Answers =<br><br> 2<br> 8<br> -2<br> -8
    11·1 answer
  • What is the area of this figure?
    11·1 answer
  • Which is the graph of y = |3x| – 2?
    13·1 answer
  • What expression is equivalent to 30 divided (3 + x)
    9·1 answer
  • PLEASE HELP ME ASAP IMDOING FINALS
    8·1 answer
  • linda races her bicycle for 132 ft. a wheel of her bicycle turns 33 times as the bicycle travels the distance. what is the diame
    5·1 answer
  • Which of the following sets of data does not contain an outlier
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!