What temperature is 20 degrees lower than 6 degree celsius

A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she

Nataly_w [17]

Answer:

The minimum sample size needed is $n = (\frac{1.96\sqrt{\sigma}}{4})^2$ . If n is a decimal number, it is rounded up to the next integer. $\sigma$ is the standard deviation of the population.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.9}{2} = 0.05$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.05 = 0.95$ , so Z = 1.645.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

How large a sample must she select if she desires to be 90% confident that her estimate is within 4 ounces of the true mean?

A sample of n is needed, and n is found when M = 4. So

$M = z\frac{\sigma}{\sqrt{n}}$

$4 = 1.96\frac{\sigma}{\sqrt{n}}$

$4\sqrt{n} = 1.96\sqrt{\sigma}$

$\sqrt{n} = \frac{1.96\sqrt{\sigma}}{4}$

$(\sqrt{n})^2 = (\frac{1.96\sqrt{\sigma}}{4})^2$

$n = (\frac{1.96\sqrt{\sigma}}{4})^2$

The minimum sample size needed is $n = (\frac{1.96\sqrt{\sigma}}{4})^2$ . If n is a decimal number, it is rounded up to the next integer. $\sigma$ is the standard deviation of the population.

4 0

3 years ago

Please help! 30 points! (it doens't say 30 points but it gives it to you after a second person answers)

Olegator [25]

950000 that is what you get when you multiply them all together hope this helps

5 0

3 years ago

You have two parents, four grandparents, eight greatgrandparents, and so forth.

Leviafan [203]

A.
In the first generation we have 2 ancestors.
In the second generation we have 4 ancestors or $2^{2}$ ancestors.
In the third generation we have 8 ancestors ot $2^{3}$ ancestors.

We can see that each succesive generation has two times more members. The sum is:
$2+4+8+16+...+ 2^{40}$

To calculate number of ancestors we can use formula for the sum of a geometric sequence. Geometric sequence is sequence of numbers that differ by a certain factor. This factor is called ratio. Formula is:
 $S= a_{1} * \frac{1- r^{n} }{1-r}$
Where:
S -> sum
a1 -> first member of a sequence
r -> ratio
n -> number of elements

For this question:
a1 = 2
r = 2
n = 40
 $S= 2* \frac{1- 2^{40} }{1-2} =2 199 023 255 550$

b.
1 generation = 25 years
40 generations = 40 * 25 = 1000 years

c.
Total number of people who have ever lived = $10^{10}$
Number of ancestors in 40 generations = $2.2*10^{12}$

The number of ancestors is greater than total number of people who have ever lived. This means that not all ancestors were distinct and that in each generation both men and women had children with more than one partner.

8 0

3 years ago

Need help horribly geometry question

Angelina_Jolie [31]

Answer:

23.31 ft

Step-by-step explanation:

Reference angle = 47°

Opp = 25 ft

Adj = x

Apply trigonometry ratio TOA:

Tan 47 = Opp/Adj

Tan 47 = 25/x

x*Tan 47 = 25

x = 25/Tan 47

x = 23.3128772 ≈ 23.31 ft (to 2 d.p)

7 0

2 years ago

What number is four times as many as 25

Nana76 [90]

Answer:

100

Step-by-step explanation:

4 x 25 = 100

7 0

3 years ago