Answer:
C
Step-by-step explanation:
A function cannot have multiple y values for one x value.
Option A lists the y values of -8 and 10 for the x value of -4. Therefore this is not a function.
Option B lists 0, 5, 10, AND 15 all for -1. This can't be a function either.
Option C does not have two of the same x values for different results. Although both 0 and 9 give you the answer of 1 for the y value, this is perfectly okay in a function. This is your answer.
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= 
1m =3.28 feet 1km= 1000m 1km=3 280 feet
120x3 280=393 600feet/h 1h=3 600sec
393 600/3 600=109.33feet/sec