A
x=y^2-9
x+9=y^2
square root both sides
+-sqrt(x+9)
        
             
        
        
        
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!
 
        
             
        
        
        
Answer: The answer is B
Step-by-step explanation:
Because it says its roaring like a freight train meaning it is loud and powerful like a train.
 
        
             
        
        
        
Answer:
320 cups of soup
Step-by-step explanation:
2/5= x/800
2/5 =.04  
800*.04 =320       x=320
2/5 = 320/800
2/5 =0.4  is equivalent to 320/800=0.4
 
        
             
        
        
        
Answer:
A farmer has enough food to feed 20 animals in his cattle for 6 days. How long would the food last if there were 10 more animals in his cattle? Here the number of animals and the number of days are in inverse proportion. Hence the food will last 4 days.