7. Solve the absolute value equation or indicate that the equation has no solution

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

How do I add the fractions <br> 1/4 + 1/7 please help me

kiruha [24]

First, you have to find the LCD. The LCD of 4 and 7 is 28, so you rewrite the fraction:
7/28
4/28

Then you add them.

8 0

3 years ago

Read 2 more answers

Please help me out on this

LenKa [72]

Answer:

D

Step-by-step explanation: since it is a open dot to the right it’s x>-3 open dot means less than or greater than going to right means greater than

5 0

2 years ago

A total of 26 bills are in a cash box. Some of the bills are one-dollar bills, and the rest are five-dollar bills. The total amo

kobusy [5.1K]

Answer:

Number of 1 $ bill = 20

Number of 5 $ bill = 6

Explanation:

Let p represent number of one dollar bolls and q represent number of five bills.

A total of 26 bills are in a cash box.

p + q = 26 ------------------------- Equation 1

The total amount of cash in the box is $50

p + 5q = 50 ------------------------- Equation 2

Equation 2 - Equation 1,

p + 5q - p -q = 50 - 26

4q = 24

q = 6

Substituting in equation 1.

p + 6 = 26

p = 20

Number of 1 $ bill = 20

Number of 5 $ bill = 6

3 0

3 years ago

4

Mazyrski [523]

Answer:

the answer is 15/4

Step-by-step explanation:

all you have to do is take the independent variable and put the sign in between.

6 0

3 years ago