So lonely have no friend

Suppose after 2500 years an initial amount of 1000 grams of a radioactive substance has decayed to 75 grams. What is the half-li

krok68 [10]

Answer:

The correct answer is:

Between 600 and 700 years (B)

Step-by-step explanation:

At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:

$A(t) = A_0 e^{(kt)}\\where:\\A(t) = Amount\ left\ at\ time\ (t) = 75\ grams\\A_0 = initial\ amount = 1000\ grams\\k = decay\ constant\\t = time\ of\ decay = 2500\ years$

First, let us calculate the decay constant (k)

$75 = 1000 e^{(k2500)}\\dividing\ both\ sides\ by\ 1000\\0.075 = e^{(2500k)}\\taking\ natural\ logarithm\ of\ both\ sides\\In 0.075 = In (e^{2500k})\\In 0.075 = 2500k\\k = \frac{In0.075}{2500}\\ k = \frac{-2.5903}{2500} \\k = - 0.001036$

Next, let us calculate the half-life as follows:

$\frac{1}{2} A_0 = A_0 e^{(-0.001036t)}\\Dividing\ both\ sides\ by\ A_0\\ \frac{1}{2} = e^{-0.001036t}\\taking\ natural\ logarithm\ of\ both\ sides\\In(0.5) = In (e^{-0.001036t})\\-0.6931 = -0.001036t\\t = \frac{-0.6931}{-0.001036} \\t = 669.02 years\\\therefore t\frac{1}{2} \approx 669\ years$

Therefore the half-life is between 600 and 700 years

5 0

3 years ago

For the square find coordinates for B without using any new variables

damaskus [11]

The geometric term described as an infinite set of points that has length but not width is called a line. It has a negligible with and depth. In geometry, a line located in the plane is defined as the set of points whose coordinates satisfy a given linear equation. A line segment however is a line connected by two dots far apart from each other and then connected. For example is the equation y=mx+b. This is a slope intercept form which is a linear equation.

6 0

3 years ago

Convert the following decimal to a percentege!!!!!! brainlest too

AfilCa [17]

Answer:

8.61%

61.29%

14.86%

20%

Step-by-step explanation:

8 0

3 years ago

Giving a test to a group of students, the grades and gender are summarized below

Anna007 [38]

Answer:

46/ 67

Step-by-step explanation:

The numbers of students irrespective of grades is;

The sum of the last roll of numbers:

10+24+ 33+ 67 = 134

The number of males irrespective of grades is the sum of the numbers in the male row ;

7 +20+ 14 +41= 82

The numbers of students with grade A is the first column at the last row and is 10;

Hence;

the probability that the student was male OR got an 'A' is

the probability that the student was male plus the probability that he/she got an 'A'.

The probability that it's a male is ;

Number of males/ total number of students

=82/134

The probability that he got an A is;

The number of students that got A/ the total number of students;

10/134

Hence

the probability that the student was male OR got an 'A' is;

82/ 134 + 10/134 = 92/134 = 46/ 67

5 0

3 years ago

What is the angle of rotation for the following figure?<br> // pls answer .

Jobisdone [24]

Answer:I THINK 180

Step-by-step explanation: HOPE THIS HELPS

5 0

3 years ago