PLS HELP GRADIENT FIRST TO ANSWER GETS BRAINLIEST

An SRS of 350 high school seniors gained an average of x¯=21 points in their second attempt at the SAT Mathematics exam. Assume

Lynna [10]

Answer:

a) $21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

b) $ME=2.58\frac{52}{\sqrt{350}}=7.17$

c) $ME=2.58\frac{52}{\sqrt{100}}=13.42$

d) D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

Step-by-step explanation:

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".

Part a

$\bar X=21$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=52$ represent the population standard deviation

n=350 represent the sample size

99% confidence interval

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

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

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that $z_{\alpha/2}=2.58$

Now we have everything in order to replace into formula (1):

$21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

Part b

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{350}}=7.17$

Part c

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{100}}=13.42$

Part d

As we can see when we reduce the sample size we increase the margin of error so the best option for this case is:

D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

6 0

2 years ago

The time to assemble the first unit on a production line is 8 hours. The learning rate is 0.81. Approximately how long will it t

pochemuha

Answer:

4.428 hours

Step-by-step explanation:

If the learning rate is 0.81, the slope of the learning curve is:

$b=\frac{ln(0.81)}{ln(2)} \\b=-0.304$

The time it takes to produce the n-th unit is:

$T_n=T_1*n^b$

If T1 = 8 hours, the time required to produce the seventh unit will be:

$T_n=8*7^{-0.304}\\T_n=4.428\ hours$

It will take roughly 4.428 hours.

3 0

3 years ago

I will give out brainliest noooooo spams ok

alekssr [168]

Answer:

0.077

Step-by-step explanation:

Marco can divide 77 by 1000 to convert it to dekagrams

There are 0.077 decagrams per 77 centagrams

5 0

3 years ago

Type the correct answer in each box. Use numerals instead of words. Consider this quadratic equation. x2 + 2x + 7 = 21 The numbe

Zolol [24]

Answer:

(a) 1

(b) 1

(c) 3.03

Step-by-step explanation:

The given quadratic equation is

Subtract 27 from both sides.

Taking out common factor.

Divide both sides by 4.

If an expression is , then we need to add , to make it perfect square.

Here, b=2, so

Add 1 on both sides.

Taking square root on both sides.

Subtract 1 from both sides.

and

Only one solution is positive.

Greatest solution is 3.031, therefore the approximate value of this solution is 3.03.

6 0

3 years ago

Read 2 more answers

72-2x=86-3x solve for x

SpyIntel [72]

Answer:

x=14

Step-by-step explanation:

1.subtract 72 from 86

2. add 3 to -2

3. get the X on one side

6 0

2 years ago