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storchak [24]
3 years ago
5

A random sample of 20 items is selected from a population. When computing a confidence interval for the population mean, what nu

mber of degrees of freedom should be used to determine the appropriate t-value?
Mathematics
1 answer:
kumpel [21]3 years ago
8 0

Answer:

For this case since the sample size is lower than 30 , n =20<30, is not appropiate use the normal standard distribution to calculate the confidence interval for the mean, and then for this case is better use the t distribution since takes in count the correction factor to approximate the distribution of the true parameter.

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

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

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 represent the sample mean for the sample  

\mu population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size  

Solution to the problem

For this case since the sample size is lower than 30 , n =20<30, is not appropiate use the normal standard distribution to calculate the confidence interval for the mean, and then for this case is better use the t distribution since takes in count the correction factor to approximate the distribution of the true parameter.

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

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

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Give an example of a quadratic equation with 2 + 3i as one of its solutions
Anastasy [175]

Answer:

Step-by-step explanation:

roots are (2+3i) and (2-3i)

reqd. eq. is (x-2-3i)(x-2+3i)=0

or (x-2)²-(3i)²=0

or x²-4x+9-9i²=0

or x²-4x+9+9=0

or x²-4x+18=0

5 0
3 years ago
Pls help !!!
Step2247 [10]
How is this 1st grade!? And also I think the answer is 3,000
8 0
2 years ago
The length of a rectangle is 5 more than the width. The perimeter is 120. What is the length, width, and area? Please HELP
Ad libitum [116K]

Answer:

l = 32.5 units, w= 27.5 units, A = 893.75 units²

Step-by-step explanation:

width is w

length is l = 5+w

P = 2( l+w) , substitute l for 5+w

P = 2(5+w+w)

P = 2(5+2w)

P = 10 +4w

P = 120

10 +4w = 120

4w = 120-10

4w = 110

w= 110/4

w= 27.5 units

l = 5+w = 5+ 27.5 = 32.5 units

A = l*w = 27.5 * 32.5 = 893.75 units ²

5 0
2 years ago
a store has a 20% off sale on pants with this discount, the price of one pair of pants before tax is $15.20. what was the origin
anastassius [24]

Answer:

19$

Step-by-step explanation:

In this problem, we have to apply the rule of three. Also, we must have present that $15.20 is the 80% of the price, because the store offers a 20% of discount. So, if $15.20 is 80%, how much would be the 100%?

Therefore, the original price of the pants is $19.

Remember that we must identified the right proportion to apply the rule of three, in this case, that proportion is the 80% with 15.20, that's the reason or fraction center of the whole operation.

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2 years ago
PLLLLLLZZZZ HELP!! MULTIPLE CHOICE!!
liubo4ka [24]
First, set 2x+7 equal to 3x-7 since they are the same angle due to the parallel lines.

2x+7=3x-7
x=14

Then, since 2x+7 and 12y+1 equals 180, put it together to find y:

(2x+7)+(12y+1)=180
(2(14)+7)+(12y+1)=180
12y+1=145
12y=144
y=12

So, x=14 and y=12. Your answer should be C!
5 0
3 years ago
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