A sphere with a diameter of 18cm. find the volume

Type the correct answer in each box. Use numerals instead of words. If necessary, use / for the fraction bar(s).

schepotkina [342]

I need you to be more specific

8 0

2 years ago

Read 2 more answers

M is inversely proportional to r if m= 9 when r= 4 find m when r=2

bazaltina [42]

m=18 when r = 2.

Step-by-step explanation:

Given,

m∝ $\frac{1}{r}$

So,

m = k× $\frac{1}{r}$ ,--------eq 1, here k is the constant.

To find the value of m when r = 2

At first we need to find the value of k

Solution

Now,

Putting the values of m=9 and r = 4 in eq 1 we get,

9 = $\frac{k}{4}$

or, k = 36

So, eq 1 can be written as m= $\frac{36}{r}$

Now, we put r =2

m = $\frac{36}{2}$

or, m= 18

Hence,

m=18 when r = 2.

4 0

2 years ago

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

2 years ago

A line includes the point (7,5)has a slope of 1.What is its equation in slope intercept form?

Lina20 [59]

Given:

Point( 7, 5)

x = 7 and y=5

slope(m) = 1

We need to first find the intercept.

Substitute x=7, y=5 and m=1 into y=mx + b and solve for intercept(b)

5 = 1(7) + b

5 = 7 + b

5 - 7 = b

-2 = b

Now, form the equation by substituting the value of the slope and intercept into y=mx + b

y = x - 2

7 0

11 months ago

mother age is three times biger than from the daughter.In 10 years mother's age will be 2 times bigger than the daughter.How man

Marrrta [24]

Answer:

20 years apart.

Step-by-step explanation:

Daughter is 10 years old, and mother is 3 times older. This makes mother 30 years old. There is a 20 year difference between them.

Ten years later, the daughter is 20 years old. Since the mother is 20 years older, she is now 40, which is 2 times older than the daughter.

6 0

2 years ago