Answer:
Step-by-step explanation:
A professor is interested in the average length of books in her library. She has divided her books into a few different categori
2 answers:
Answer:
<h2>21 books approximately.</h2>Step-by-step explanation:
First of all we need to find the proportion of the sample. To do that, we sum all the books and then divide by the sample we need, which is 50
, because we need 50 books among 691 total.
Now, with this ratio, which is the same for all sample we would make here, we find the stratified sample of books, specifically, for sports books which are 290.
Thefore, she should take 21 sports books.
Remember that stratified sampling refers to a type of sampling method where the population is divided into separate groups, which in this case represented the type of books. Then, we use a "probability" sample, or a proportion of the sample to apply it.
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Answer:
4.27%
Step-by-step explanation:
We have been given that college students average 8.6 hours of sleep per night with a standard deviation of 35 minutes. We are asked to find the probability of college students that sleep for more than 9.6 hours.
We will use z-score formula to solve our given problem.
z = z-score,
x = Random sample score,
= Mean,
= Standard deviation.
Before substituting our given values in z-score formula, we need to convert 35 minutes to hours.
Now, we need to find .
Using formula , we will get:
Using normal distribution table, we will get:
Therefore, 4.27% of college students sleep for more than 9.6 hours.