The radioactive isotope of lead, Pb-209, decays at a rate proportional to the amount present at time t and has a half-life of 3.3 hours. If 1 gram of this isotope is present initially, how long will it take for 70% of the lead to decay? (Round your answer to two decimal places.)

Answer:

8,-9,9

Step-by-step explanation:

Answer:

10

Step-by-step explanation:

10+3 = 13

13 x 7 = 91

Answer:

7(3x)=91

21x=91

x=91/21

Answer:

x = 14

Step-by-step explanation:

Please note, the word trapezium is a synonym for the word trapezoid.

This problem gives one the area of the trapezoid, a well as one of the measurements of a base and the height of the figure. One is asked to find the length of the other base. This can be done by using the formula to find the area of a trapezoid. This formula is the following,

[tex]A=(h)(\frac{b_1+b_2}{2})[/tex]

Where (A) represents the area of a trapezoid, ([tex]b_1[/tex]) and ([tex]b_2[/tex]) represents the bases and (h) represents the height. Substitute in the given values and solve for the unknown base.

[tex]b_1=7\\h=6\\A=84[/tex]

[tex]A=(h)(\frac{b_1+b_2}{2})\\[/tex]

Substitute,

[tex]84=6(\frac{7+b_2}{2})\\[/tex]

Inverse operations,

[tex]84=6(\frac{7+b_2}{2})[/tex]

[tex]14=\frac{7+b_2}{2}[/tex]

[tex]28=7+b_2[/tex]

[tex]14=b_2[/tex]

Answer:

Rock D.

Step-by-step explanation:

We can assume that the force that the catapult does is always the same.

So, here we need to remember Newton's second law:

F = m*a

force equals mass times acceleration.

Where acceleration is the rate of change of the velocity.

So, if we want the rock to hit closer to the catapult, the rock must be less accelerated than rock B.

So, we can rewrite:

a = F/m

So, as larger is the mass of the rock, smaller will be the acceleration of the rock after it leaves the catapult (because the mass is in the denominator). So if we want to have a smaller acceleration, we need to choose a rock with a larger mass than rock B.

Assuming that the mass depends on the size, the only one that has a mass larger than rock B is rock D.

So we can assume that rock D is the correct option.

Answer:

the answer is B

Step-by-step explanation:

9514 1404 393

Answer:

  64.6

Step-by-step explanation:

One standard deviation is 4.3. Then +2 standard deviations is ...

  (+2)(4.3) = +8.6

This amount added to the mean gives ...

  56 +8.6 = 64.6 . . . . +2σ from the mean

Answer:

22 kg

Step-by-step explanation:

1297 cans * (17 grams)/(1 can) * (1 kg)/(1000 g) = 22.049 kg

Answer: 22 kg

Answer:

AnD = {8,10}

Step-by-step explanation:

A = {2, 4, 6, 8 ,10 ...}

B = {1, 3, 5, 7 ,9 ...}

C = {,2 ,3 ,4 ,5 ...}

D = { 8, 9 ,10 ,11 ...}

AnD = {8, 10}

Answer:

[tex]\frac{22}{3}[/tex]

Step-by-step explanation:

x + y + y + z + z + x = 2x + 2y + 2z = 22

x + y + z = 22

22 ÷ 3 = [tex]\frac{22}{3}[/tex]

Question 1

Question 2

Question 3

Answer:

84 rows

84 plants on each row

Step-by-step explanation:

Given

[tex]Plants = 7056[/tex]

Required

The number of rows

Since the number of rows (r) and the plants on each row (p) are the same, then the area to be planted on is:

[tex]Plants = r * p[/tex]

Where

[tex]r =p[/tex]

So, we have:

[tex]Plants = r * r[/tex]

[tex]Plants = r^2[/tex]

This gives:

[tex]7056 = r^2[/tex]

Take square roots

[tex]84 = r[/tex]

Rewrite

[tex]r = 84[/tex]

Answer:

AC = 28

Step-by-step explanation:

Ok, we know that:

Points A, B, and C are collinear.

Point B is between A and C.

We want to find the length AC (distance between A and C), if we know that:

AB = 16

BC = 12

Ok, knowing that B is between the other points, we know that:

AB + BC

defines the total length of the segment that connects the 3 points.

Thus, if we define this segment as a length, we only use the endpoints, A and C.

Then we have that:

AB + BC = AC

now we can solve this:

16 + 12 = AC

28 = AC

Sui believes that the two cylinders have an equal volume is correct.

The volume of cylinder = Base area×Height

=(πr²)×(height)

This is also true for oblique cylinder.

Both cylinders have same height and radius also so, both cylinders have equal volume.

V=πr²h

V=π×(5)²×11.5

V=903.208m³

It can also be visualized that the oblique cylinder have circular pieces. These pieces can be solid together to form a regular cylinder with the same height (i.e. 11.4 m). So both the cylinders have equal volume.

A cylinder is a three-dimensional shape in geometry. A cylinder is round and has a top and bottom in the shape of a circle. The top and bottom are flat and always the same size.

Thus, Sue is correct, and it's true that the two cylinders shown in the diagram have equal volumes.

Learn more about cylinders here,

https://brainly.com/question/15891031

#SPJ2

Answer: 13

Step-by-step explanation:

Given

The number is 2925

The prime factorization of 2925 is

[tex]\Rightarrow 2925=3\times 3\times 5\times 5\times 13\\\Rightarrow 2925=3^2\times 5^2\times 13[/tex]

To make 2925 a perfect square, we have to eliminate 13 from it, so divide 2925 by 13 to make it a perfect square

The perfect Sqaure becomes [tex](3\times 5)^2=225[/tex]

Answer:6/6

Step-by-step explanation:

1/6 divide 6

Keep

Flip

Change

your gonna keep 1/6 as a fraction

then flip the second fraction so 6 would’ve been 6/1 but it’s gonna flip so it should look like this 1/6

after you will change the  sign so the division will become multipliaction so it should look like 1/6 x 6/1 which will equal to 6/6

Answer:

33

1/2(83-50)=25

83-x=50

x=33

Answer:

3,872.316

Step-by-step explanation:

Answer:

to nearest hundreds it would be: 3,900

Step-by-step explanation:

872 it closer to 900 than 800

Answer:

70910 not sure

Step-by-step explanation:

70.91 x 10 = 709.1 70.91 x 100 = 7,091 70.91 x 1,000 =

Answer:

The answer is below

Step-by-step explanation:

12 inches = 1 ft.

6 inches = 6 inches * (1 ft./12 inches) = 0.5 ft.

Therefore the diameter of the cast iron (D) = 6 inches = 0.5 ft.

The area of cast iron (A) = πD²/4 = π(0.5)²/4 = 0.196 ft²

The velocity (V) = 6 ft./s, the acceleration due to gravity (g) = 32.2 ft./s²

ε/D = 0.0004 ft./ 0.5 ft. = 0.0008

Using the moody chart, find the line ε/D = 0.0008 and determine the point of intersection with the vertical line R = 2.7 * 10⁵. Hence we get f = 0.02.

The head loss (h) is:

[tex]h_f=f*\frac{L}{d}* \frac{V^2}{2g}=0.02*\frac{200\ ft}{0.5\ ft} *\frac{(6\ ft/s)^2}{2*32.2\ ft/s^2}=4.5\ ft[/tex]

The pressure drop (Δp) is:

Δp = ρg[tex]h_f[/tex] = [tex](62.4\ lbf/ft^3)(4.5\ ft)= 280\ lbf/ft^2[/tex]

9514 1404 393

Answer:

  10

Step-by-step explanation:

Possible tower heights using 3 blocks are ...

  {9, 10, 11, 12, 14, 15, 16, 19, 20, 24}

There are 10 different heights possible.

_____

Each block can be used 1, 2, or 3 times.

Using a 3 in block as the smallest, we have ...

  3+3+3 = 9

  3+3+4 = 10

  3+3+8 = 14

  3+4+4 = 11

  3+4+8 = 15

  3+8+8 = 19

Using a 4-in block as the smallest, we have ...

  4+4+4 =12

  4+4+8 = 16

  4+8+8 = 20

And ...

  8+8+8 = 24

Answer:

-9

Step-by-step explanation:

Two-thirds of a number is negative six. The number is -9. Let the number is x, 2/3x =-6, x=-6x3/2=-9.

Answer:

5

Step-by-step explanation:

(5/6) / (1/6) = 5

Answer:

5 batches

Step-by-step explanation:

Divide yesterday's batches by the usual.

(5/6)/(1/6) = 5

Since it only takes 1/6 to make a batch and they used 5x that we know they made 5 batches.

Answer:

x = 11.

Step-by-step explanation:

√(x - 2) + 8 = x

√(x - 2) = x - 8

Square both sides:

x - 2 = x^2 - 16x + 64

x^2 - 17x + 66 = 0

(x - 6)(x - 11) = 0

x = 6, 11.

Test for an extraneous solution:

x = 6:

Left side = √(6-2) + 8 = 10

Right side = 6

x = 11:

Left side = √9 + 8 = 11

Right side =  11

So x = 6 is extraneous.

Answer:

[tex]n = (\frac{1.96\sqrt{\pi(1-\pi)}}{M})^2[/tex]

The sample size needed is n(if a decimal number, round up to the next integer), considering the estimate of the proportion [tex]\pi[/tex](if no previous estimate use 0.5) and M is the desired margin of error.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of [tex]\pi[/tex], and a confidence level of [tex]1-\alpha[/tex], we have the following confidence interval of proportions.

[tex]\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

In which

z is the z-score that has a p-value of [tex]1 - \frac{\alpha}{2}[/tex].

The margin of error is of:

[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

95% confidence level

So [tex]\alpha = 0.05[/tex], z is the value of Z that has a p-value of [tex]1 - \frac{0.05}{2} = 0.975[/tex], so [tex]Z = 1.96[/tex].

Needed sample size:

The needed sample size is n. We have that:

[tex]M = z\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

[tex]M = 1.96\sqrt{\frac{\pi(1-\pi)}{n}}[/tex]

[tex]\sqrt{n}M = 1.96\sqrt{\pi(1-\pi)}[/tex]

[tex]\sqrt{n} = \frac{1.96\sqrt{\pi(1-\pi)}}{M}[/tex]

[tex](\sqrt{n})^2 = (\frac{1.96\sqrt{\pi(1-\pi)}}{M})^2[/tex]

[tex]n = (\frac{1.96\sqrt{\pi(1-\pi)}}{M})^2[/tex]

The sample size needed is n(if a decimal number, round up to the next integer), considering the estimate of the proportion [tex]\pi[/tex](if no previous estimate use 0.5) and M is the desired margin of error.

Answer:

69

Step-by-step explanation:

xvusvsuvtuvqYSQY

Answer:

b. x^4 varies directly as y.

Step-by-step explanation:

x^4 = 7×y

x^4 is proportional to y.

Answer:

Step-by-step explanation:

We see the data is not uniform. One of the prices is very high compared to the others. Since there is an outlier, the median is the best measure of central tendency.

This is the second option.