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vfiekz [6]
2 years ago
13

21²/0.219 to 2 significant figures​

Mathematics
2 answers:
bogdanovich [222]2 years ago
6 0
The answer is 2000…..
Oksanka [162]2 years ago
3 0
21^2/0.219 = 2013.69863
2 significant figures are the 20, so the answer is 2000
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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
tester [92]

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

6 0
3 years ago
Juan and his little brother Miquel ran around a circular track together. Juan ran on the inner track, which has a radius of 30 f
MArishka [77]

Answer:

he would have had to run 20 more feet then Juan

Step-by-step explanation:

5 0
3 years ago
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When the function ƒ(x) = 4x−2 is evaluated for x = 3, the output is:<br> -4<br> -6<br> -16<br> -none
Mkey [24]

Answer:

None

General Formulas and Concepts:

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right<u> </u>

<u>Algebra I</u>

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Step-by-step explanation:

<u>Step 1: Define</u>

f(x) = 4x - 2

x = 3

<u>Step 2: Evaluate</u>

  1. Substitute in <em>x</em> [Function]:                                                                                f(3) = 4(3) - 2
  2. Multiply:                                                                                                             f(3) = 12 - 2
  3. Subtract:                                                                                                            f(3) = 10
7 0
3 years ago
What is the surface area of the​ solid?
sertanlavr [38]

Answer:

othe large one is 234 i ran out of time sorry i didnt get  circleto t

Step-by-step explanation:

5 0
3 years ago
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Help please.........,
Xelga [282]

y-6 = -4(x+1)

y-6 = -4x-4

add 6 to each side

y=-4x+2

A is the correct answer

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3 years ago
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