Answer: 7/10
Step-by-step explanation:
First you add the total number of marbles. Then, you take the total number of blue marbles, and make that your denominator. The total number of marbles is your numerator.
Answer:
A 99% confidence interval will be wider than a 95% confidence interval
Step-by-step explanation:
From the question we are told that
The 95% confidence interval for for the mean foot length for students at the college is found to be 21.709 to 25.091 cm
Generally the width of a confidence interval is dependent on the margin of error.
Generally the margin of error is mathematically represented as
From the above equation we see that
Here 
is the critical value of the half of the level of significance and this value increase as the confidence level increase
Now if a 99% confidence level is used , it then means that the value of
will increase, this in turn will increase the margin of error and in turn this will increase the width of the confidence interval
Hence a 99% confidence interval will be wider than a 95% confidence interval
Answer:
d.
Step-by-step explanation:
Hello!
The objective of this test is to know if aerobic exercise modifies hippocampus activity. A random sample of 120 elderly men and women was taken and divided into two groups.
Group 1: Walked around a track three times a week.
Group 2: Did a variety of less aerobic exercises, including yoga and resistance training with bands.
After a year their brains were scanned showing that group 1 had an increase of 2% in their hippocampus and group 2 showed a decrease of 1.4%
a. True, this type of observational study can be the prelude to a more formal statistical study.
b. True, the explanatory variable is "type of exercise", it's the variable that the investigator suspects influence the hippocampus volume.
c. True, the objective of this experiment is to test if there is any modification on hippocampus volume, that's why the volume of the hippocampus was measured, before and after a year of exercise.
d. False, this is an observational study, you cannot establish a causal relationship between the two variables. Just inform you that there seems to be an association. To be able to generalize the results to all elderly population you need a more formal statistical experiment to support your conclusions.
I hope it helps!
