Hee Sun wants to estimate the average world length in a book. She randomly chooses 20 words in the book, as shown. Based on this
sample, which is the best estimate of the mean word length in the book? (I chose D, but I’m not sure if I’m correct.)
1 answer:
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Answer:And we can find this probability with this difference:
And in order to find these probabilities we use tables for the normal standard distribution, excel or a calculator.
So then the best answer would be 21.82 %
Step-by-step explanation:
Previous concepts
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".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the time it takes to trim a tree of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:And we can find this probability with this difference:
And in order to find these probabilities we use tables for the normal standard distribution, excel or a calculator.
So then the best answer would be 21.82 %