Anybody? I'm pretty sure calculators don't do it right so..please no calculators. ;-;
2 answers:
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Answer:
So the answer for this case would be n=247 rounded up to the nearest integer
Step-by-step explanation:
We know that the standard deviation is :
represent the deviation
The margin of error is given by this formula:
(a)
And on this case we have that ME =25 and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
The critical value for 95% of confidence interval now can be founded using the normal distribution and the critical value would be , replacing into formula (b) we got:
So the answer for this case would be n=247 rounded up to the nearest integer
Answer:
Therefore the variance on the data set is 8.3
Step-by-step explanation:
In order to find the variance of the set of data we first need to calculate the mean of the set, which is given by:
mean = sum of each element / number of elements
mean = (5 + 8 + 2 + 9 + 4)/5 = 5.6
We can now find the variance by applying the following formula:
So applying the data from the problem we have:
s² = [(5 - 5.6)² + (8 - 5.6)² + (2 - 5.6)² + (9 - 5.6)² + (4 - 5.6)²]/(5 - 1)
s² = [(-0.6)² + (2.4)² + (-3.6)² + (3.4)² + (-1.6)²]/4
s² = [0.36 + 5.76 + 12.96 + 11.56 + 2.56]/4 = 8.3
Therefore the variance on the data set is 8.3