hehe pls help i nneed it

Answer:

2.5 half-lives

Step-by-step explanation:

Find [tex]t_{h}[/tex] in [tex]N(t)=N_{0}e^{-kt}[/tex] given [tex]N(t) = 2, N_{0} =64,t=\frac{25}{2}[/tex]

[tex]N(t)[/tex] is the amount after the time [tex]t[/tex], [tex]N_0[/tex] `is the initial amount, [tex]t_{h}[/tex] is the half-life

We know that after half-life there will be twice less the initial quantity:

[tex]N(t_{h})=\frac{N_{0} }{2}=N_{0}e^{kt_{h} }[/tex].

Simplifying gives [tex]\frac{1}{2} =e^{-kt_h} or k = -\frac{In(\frac{1}{2}) }{t_{h} } .[/tex]

Plugging this into the initial equation, we obtain that [tex]N(t)=N_{0}e^\frac{In(\frac{1}{2}) }{t_{h} }[/tex]or [tex]N(t)= N_{0} (\frac{1}{2})^\frac{t}{t_h}.[/tex]

Finally, just plug in the given values and find the unknown one.

From [tex]2=64(\frac{1}{2})^\frac{\frac{25}{2} }{t_h}[/tex], we have that [tex]t_h[/tex] = [tex]\frac{25 In (2)}{2 In (32)\\}[/tex]

So you should get: [tex]t_{h} =\frac{25 In (2)}{2 In (32)\\}=2.5.[/tex]

The number of half-lives that transpired during this time period is equal to 2.5 hours.

Given the following data:

Time = 12.5 hours.

Initial mass = 64 grams.

Remaining mass = 2.0 grams.

Mathematically, the amount of a radiocative element that is remaining after time (t-hours) is given by this formula:

[tex]ln(\frac{A}{A_0} )=ln(\frac{1}{2} )\frac{t}{H}[/tex]

Where:

Substituting the given parameters into the formula, we have;

ln(2/64) = ln(1/2) × 12.5/H

-3.466 = -0.693 × 12.5/H

H = 12.5 × -0.693/-3.466

H = 12.5 × 0.1999

H = 2.5 hours.

Read more on half-life here: https://brainly.com/question/25750315

Answer:

a) 75%.

b) 84%

c) Within 2 standard deviations from the mean is 95%. The normal distribution has a higher percentage of observations closer to the mean than a non normal distribution, so this percentage is larger.

Step-by-step explanation:

Empirical Rule:

The Empirical Rule states that, for a normally distributed random variable:

Approximately 68% of the measures are within 1 standard deviation of the mean.

Approximately 95% of the measures are within 2 standard deviations of the mean.

Approximately 99.7% of the measures are within 3 standard deviations of the mean.

Chebyshev Theorem:

The Chebyshev Theorem can also be applied to non-normal distribution. It states that:

At least 75% of the measures are within 2 standard deviations of the mean.

At least 89% of the measures are within 3 standard deviations of the mean.

An in general terms, the percentage of measures within k standard deviations of the mean is given by [tex]100(1 - \frac{1}{k^{2}})[/tex].

In this question:

Mean: 6.3 hours

Standard deviation: 1.6 hours

(a) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 3.1 and 9.5 hours.

3.1 = 6.3 - 2*1.6

9.5 = 6.3 + 2*1.6

Within 2 standard deviations, so the minimum percentage is 75%.

(b) Use Chebyshev's theorem to calculate the minimum percentage of individuals who sleep between 2.3 and 10.3 hours.

How many standard deviations from the mean?

One standard deviation is 1.6

These measures are 10.3 = 6.3 = 6.3 - 2.3 = 4. This is k standard deviations, in which

[tex]k = \frac{4}{1.6} = 2.5[/tex]

The minimum percentage is:

[tex]100(1 - \frac{1}{k^{2}}) - 100(1 - \frac{1}{2.5^{2}}) = 84%[/tex]

So 84%.

(c) Assume that the number of hours of sleep follows a bell-shaped distribution. Use the empirical rule to calculate the percentage of individuals who sleep between 3.1 and 9.5 hours per day.

Within 2 standard deviations from the mean is 95%. The normal distribution has a higher percentage of observations closer to the mean than a non normal distribution, so this percentage is larger.

Answer:

A

Step-by-step explanation:

2.5 x 3.4 = 8.5

Answer:

96 people

Step-by-step explanation:

i used a calculator

Answer:

square pyramid

Step-by-step explanation:

Answer:

star

Step-by-step explanation:

Answer:

Step-⚫️_by-step explanation:

Answer:

Stratified sampling

Step-by-step explanation:

key word "groups"

The sampling scheme did she used is stratified sampling.

It is a method of sampling where the division of the population should be split into the smaller subgroup called a strata. The strata should be created depending upon on the members shared like the income etc. Here the sample should be needed for applicants for across the US also it randomly selects the applicants for each state.

So, The sampling scheme did she used is stratified sampling.

Learn more about a sample here: https://brainly.com/question/24526520

Answer:

15

Step-by-step explanation:

a:b::c:d

a/b=c/d .......(eq 1)

let a=0.2, b=0.5, c=6, d=x

Not put values in eq 1

0.2/0.5 = 6/a

By cross multiplication we get:

0.2xa = 6x0.5

0.2a = 3

Dividing by 0.2 on both sides we get

0.2a/0.2 = 3/0.2

a = 15

Therefore The fourth proportional is 15

Answer:

yes, yes, no, no

Step-by-step explanation:

Answer- y = - x/2 + 5

Step by step - Replace f (x) with y.

Y = - 2x + 10

Interchange the variables.

x= -2y + 10

Solve for y.

Y= x/2 +5

Answer:

two solutions work: x = 5 + [tex]\sqrt{19}[/tex] and x = 5 - [tex]\sqrt{19}[/tex]

Step-by-step explanation:

x + 6 ( 1/x ) = 10

x^2 + 6 = 10x

x^2 - 10x + 6 = 0

x = 5 + [tex]\sqrt{19}[/tex], 5 - [tex]\sqrt{19}[/tex]

Answer:

Length of arc AD = 15.7 cm

Step-by-step explanation:

Length of arc = [tex]\frac{\theta}{360}(2\pi r)[/tex]

Here, θ = Central angle subtended by the arc

r = radius of the circle

From the picture attached,

Central angle subtended by arc AD = 360° - (180° + 66.4°)

                                                            = 113.6°

Length of arc AD = [tex]\frac{(113.6)}{360}(2\pi )(7.9)[/tex]

                             = [tex]\frac{113.6}{360}(2)(3.14)(7.9)[/tex]

                             = 15.655 cm

                             ≈ 15.7 cm

Length of arc AD = 15.7 cm

Answer:

12.4

Step-by-step explanation:

Just did it.

Answer:

88.2 is your answer.

Answer:500

Step-by-step explanation:on delta math

Answer:

yes

Step-by-step explanation:

2 + 16(1) = 18

2+16 = 18

2(2) + 11(1) = 15

4+11=15

Answer: c is the answer

Step-by-step explanation: the formuals for volume is length x width x height, 6x7x5, which is 210

Answer: C

Step-by-step explanation: Easy, just do length x width x height(l x w h). So, 6x7x5 = 210

Answer:

the answer is 36

Step-by-step explanation:

beacuse if we use the pythagorean theorem for 9 and 12 we get 15 which means that the perimeter is P=9+15+12=36

Answer: The answer is C

Step-by-step explanation:

C is the answer because the base is +2 and the coefficent  is  1/2 which is rise over run so you go up one space and to the right two spaces.          

Answer:

3/8

Step-by-step explanation:

Answer:

B

Step-by-step explanation:

√c^2-b^2

√15^2-9^2

√225-81

√144

= 12

B

Answer:

That is wrong bc it says quotient and quotient means a division sign which i dont see on your answer,

Step-by-step explanation:

The correct answer should be...

3/2x

Im srry if wrong (and the "/" means division)

Answer:

≈3.99938

Step-by-step explanation:

Answer:

[tex]3a(3a - 2)[/tex]

Step-by-step explanation:

[tex]3(3a ^{2} - 2a) \\a(3a - 2) [/tex]

Answer:

Answer as a fraction: 4/15

Answer as a decimal: 0.267

The decimal version is approximate rounded to three decimal places.

Step-by-step explanation:

6 apples, 4 peaches

6+4 = 10 pieces of fruit total

The probability of picking an apple is 6/10 = 3/5

After you pick and eat the apple, there are 10-1 = 9 pieces of fruit left. Also, the probability of picking a peach is 4/9, as there are 4 peaches out of 9 fruit left over.

Multiply out 3/5 and 4/9 to get (3/5)*(4/9) = (3*4)/(5*9) = 12/45 = 4/15

Using a calculator, 4/15 = 0.267 approximately.

Answer:

Her friend got the better deal.

Step-by-step explanation:

For Jillians equation look at

$22.56/4 = $6.39 per CD

For her friends equation look at

$18.45/3 = $6.15 per CD

Jillian's friend got the better deal because she paid less per CD as shown in the equations above.