It is the sample mean age of 21.7.
about 25
68 % is about one standard deviation - so there score would be between 64 and 80 (72 +/- 8)
The null hypothesis could be that the 40 students are a sample from the same (or similar) population.
There are approximately 16.4% of students who score below 66 on the exam.
i y=use Z-test
Standard deviation is 0.
To see how wide spread the results are. If the average (mean) grade for a certain test is 60 percent and the standard deviation is 30, then about half of the students are not studying. But if the mean is 60 and the standard deviation is 5 then the teacher is doing something wrong.
about 25
IQ scores for adult students age 25-45 have a bell-shaped distribution with a mean of 100 and a standard deviation of 15.sing the Empirical Rule, what percentage of adult students age 25-45 have IQ scores between 70 and 130?
68 % is about one standard deviation - so there score would be between 64 and 80 (72 +/- 8)
The null hypothesis could be that the 40 students are a sample from the same (or similar) population.
There are approximately 16.4% of students who score below 66 on the exam.
Not possible to tell you without knowing how many students' there are, and what distribution you wish to use (i.e normal distribution, t-distribution etc...)
i y=use Z-test
(x-400)/100=1.882 x=588.2
0.9699
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