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Lady_Fox [76]
3 years ago
9

A manufacturer reported a sample mean = 22.0 g and a sample standard deviation = 2.5 g based on a sample of 20 of their products

. They hope to design future quality control tests to satisfy several criteria:  The calculated error for a sample set (the error is the difference between the true mean and mean of the sample set) does not exceed 2.0 g.  To save money on those tests, they want to collect as few samples as possible.  They want more than 90% of the confidence intervals they calculate to include the true mean. What value of n would you recommend for future tests?
Mathematics
1 answer:
tester [92]3 years ago
6 0

Answer:

n=(\frac{1.640(2.5)}{2})^2 =4.2 \approx 5

So the answer for this case would be n=5 rounded up to the nearest integer

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".

\bar X=22 represent the sample mean

\mu population mean (variable of interest)

s=2.5 represent the sample standard deviation

n represent the sample size  

ME = 2 represent the margin of error accepted

Solution to the problem

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

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

The margin of error is given by this formula:

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

And on this case we have that ME =2 and we are interested in order to find the value of n, if we solve n from equation (2) we got:

n=(\frac{z_{\alpha/2} s}{ME})^2   (3)

We can use as estimator for the population deviation the sample deviation \hat \sigma = s

The critical value for 90% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.05;0;1)", and we got z_{\alpha/2}=1.640, replacing into formula (3) we got:

n=(\frac{1.640(2.5)}{2})^2 =4.2 \approx 5

So the answer for this case would be n=5 rounded up to the nearest integer

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Anyone know the answers to 1, 2, 3, 4, 5
muminat

Answer:

1. C. 1/4(4) + 1/4(9) (A, 1/4(13), is essentially C simplified (without figuring it out).)

2. G - -4

3. A - -4(-5) + (-4)x

4. J - 1/6x + 1/6y

5. A - 60(10 + 2)

Step-by-step explanation:

1.

1/4(4 + 9) <em>We can distribute 1/4 into 4 and 9.</em>

1/4(4) + 1/4(9) <em>Now while we have our answer, this can be further simplified.</em>

1/4(13) <em>What's on the left is the simplified 2-term equation.</em>

<em>So really, either C or A will be the answer. But due to the format of #3, I put C as my answer. B & D were out because there wasn't any extra multiplication.</em>

2.

-2/5(15 - 5) <em>Subtract 5 from 15 to get 10.</em>

-2/5(10) <em>Multiply -2/5 by 10 to get -20/5</em>

-20/5 <em>Divide -20 by 5 to get -4.</em>

-4, so G is the answer. <em>This was negative, so H & J were out to begin with. F was out as soon as I solved the problem.</em>

3.

-4(-5 + x) <em>Distribute -4 into -5 + x.</em>

-4(-5) + (-4)x, so A is the answer. <em>Don't get tricked! B may look right, but there should be a negative sign in front of the 5, hence why it's incorrect.</em>

4.

1/6(x + y) <em>Distribute 1/6 into x + y.</em>

1/6x + 1/6y, so J is the answer. <em>F & G are already out because you don't multiply the variables by each other. H is also out because there wasn't any multiplication involved other than x + y being multiplied by 1/6.</em>

5.

Only 60(10 + 2) would have worked, so A is the answer. The tickets would have cost 720 dollars (600 + 120). <em>B would have equated to 624 (24 + 600), C would have been 132 (6 * 22), and D would have been 600. (10 * 60).</em>

6 0
3 years ago
F
galina1969 [7]
It’s F because I took the test
8 0
3 years ago
Zoe babysat for x+3 hours yesterday.she earned x-2 dollars per hour.write a polynomial expression that represents the amount Zoe
vekshin1

Answer:

y=3x+2

Step-by-step explanation:


5 0
3 years ago
A weather forecaster says the temperature will be about -5C “give or take” 10 degrees. What is the greatest possible temperature
bagirrra123 [75]

Minimum: -15C

Max: 5C

4 0
3 years ago
Kyle is stringing a necklace with beads he puts black beads on 5/8 of the string and white beads on 1/4 of the string Kyle think
Alexeev081 [22]

Answer:Kyle’s claim is not reasonable

Step-by-step explanation:

Total length of the string of the necklace that Kyle covered with black beads is 5/8.

Total length of the string of the necklace that Kyle covered with white beads is 1/4.

Total length of the string of the necklace that Kyle covered with black beads and white beads is would be

1/4 + 5/8 = 7/8 = 0.875

Kyle thought that he will cover 6/12 of the string with beads. 6/12 = 0.5

It means that he covered more than 6/12. Kyle's claim was wrong

3 0
3 years ago
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