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podryga [215]
3 years ago
10

Find the minimum sample size necessary to be 99% confident that the population mean is within 3 units of the sample mean given t

hat the population standard deviation is 29. (a) What is the critical value that corresponds to the given level of confidence? Round your answer to two decimals, and remember that critical values are always positive.
Mathematics
1 answer:
olga55 [171]3 years ago
3 0

Answer:

623

Step-by-step explanation:

Given that margin of error (E) = 3 unit, standard deviation (σ) = 29, sample size (n) = ?

a) The confidence (C) = 99% = 0.99

α = 1 - C = 1 - 0.99 = 0.01

α/2 = 0.01 / 2 = 0.005

From the normal distribution table, The z score of α/2 (0.005) is the critical value and it corresponds to the z score 0.495 (0.5 - 0.005) which is 2.58.

critical\ value = z_{\frac{\alpha}{2} }=z_{0.005}=2.58\\

b) The margin of error (E) is given as:

<h3>E=z_{\frac{\alpha}{2} }*\frac{\sigma}{\sqrt{n} }\\\\\sqrt{n}= z_{\frac{\alpha}{2} }*\frac{\sigma}{E }\\ \\n=( z_{\frac{\alpha}{2} }*\frac{\sigma}{E })^2\\\\Substituting:\\\\n=(2.58*\frac{29}{3} )^2=622.0036\\\\\\n=623(to\ the \ next\ whole\ number)</h3>

The minimum sample size (n) is 623

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Answer:

y = 2.31x + 309.35

Step-by-step explanation:

Whenever you are checking for a best fitting equation you want to check if it has a constant slope.  If it does then the relation is linear and super easy.

So, since the t values are increasing by the same amount you want to see if the y values are  too.  And they are, each population entry is increasing by 2.31, this is the slope.  

Also, keep in mind you can caluclate slope with the equation \frac{y_2-y_1}{x_2-x_1}  here x is replaced by t though.

Now, since we know it's linear and we know the slope we can find the equation with the formula  y - y1 = m(x - x1) where again, x is replaced by t and m is the slope 2.31

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