What is the answer to 3 and 4?

A doctor wants to estimate the mean HDL cholesterol of all 20- to 29-year-old females. The number of subjects needed to estima

Ludmilka [50]

Answer:

$n=(\frac{1.64(14.7)}{3})^2 =64.57 \approx 65$

So the answer for this case would be n=65 rounded up to the nearest integer

And the sample size would decrease by 160-65=95 subjects

Step-by-step explanation:

1) Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

ME represent the margin of error

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

2) Solution to the problem

Since the new Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.05,0,1)".And we see that $z_{\alpha/2}=1.64$

Assuming that the deviation is known we can express the margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (a)

And on this case we have that ME =\pm 3 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} \sigma}{ME})^2$ (b)

Replacing into formula (b) we got:

$n=(\frac{1.64(14.7)}{3})^2 =64.57 \approx 65$

So the answer for this case would be n=65 rounded up to the nearest integer

And the sample size would decrease by 160-65=95 subjects

8 0

3 years ago

Greg bought a new car for £18000.

Whitepunk [10]

Answer:

£9318.96

Step-by-step explanation:

18000×0.7×0.86^(2)=£9318.96

3 0

3 years ago

Which answer is equivalent to ??? Help please

grigory [225]

Answer:

$\large\boxed{\dfrac{36}{25}}$

Step-by-step explanation:

$\text{Use}\ a^{-n}=\dfrac{1}{a^n}\\\\\dfrac{5^{-2}\cdot9}{2^4\cdot4^{-3}}=(5^{-2}\cdot9):(2^4\cdot4^{-3})=\left(\dfrac{1}{5^2}\cdot9\right):\left(2^4\cdot(2^2)^{-3}\right)\\\\\text{use}\ (a^n)^m=a^{nm}\\\\=\left(\dfrac{1}{25}\cdot9\right):(2^4\cdot2^{-6})\\\\\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=\dfrac{9}{25}:2^{4+(-6)}=\dfrac{9}{25}:2^{-2}=\dfrac{9}{25}:\dfrac{1}{2^2}=\dfrac{9}{25}:\dfrac{1}{4}=\dfrac{9}{25}\cdot\dfrac{4}{1}=\dfrac{36}{25}$

7 0

4 years ago

Find the surface area of the net below.

dedylja [7]

Answer:

472 in²

Step-by-step explanation:

This net is made up of 3 identical rectangles and 2 identical triangles.

Area of a rectangle = width x length

Area of a triangle = 1/2 x base x height

Rectangle

width = 8 in
length = 19 in

Triangle

base = 8 in
height = 2 in

Surface Area

SA = 3(8 x 19) + 2(0.5 x 8 x 2)

⇒ SA = 456 + 16

⇒ SA = 472 in²

5 0

3 years ago

I need to put the words in place

marusya05 [52]

The photo isn’t loading

8 0

3 years ago