Answer: 
Step-by-step explanation:
Given : Sample size : n= 9
Degree of freedom = df =n-1 =8
Sample mean : 
sample standard deviation : 
Significance level ; 
Since population standard deviation is not given , so we use t- test.
Using t-distribution table , we have
Critical value = 
Confidence interval for the population mean :

90% confidence interval for the mean value will be :






Hence, the 90% confidence interval for the mean value= 
Answer:
14
Step-by-step explanation:
12:6=2
12+2=14
so her brother it's 14 years old
I’m pretty sure it would be a and b
You have to do the opposite
22-17=5
5x3=15
15+13=28
28/4=7
The answer is 7. You can check this by doing what it says and if it makes 22, it’s correct. (I’ve already checked it) :)
White, 7/10= 14/20
It has the largest chance of being selected at random