Answer: 
Step-by-step explanation:
Given : Sample size : 
Sample mean : 
Standard deviation : 
Significance level : 
Critical value : 
Formula to find the confidence interval for population mean :-

Hence, a 90% confidence interval estimate of the population mean of all students = 
Answer:
What is y?
Step-by-step explanation:
For the given vectors
and 
The dot product of vectors a and b is defined as = 
So, 

= -16+12
= -4
Answer:
well for me it's because
Step-by-step explanation:
Of the raise to power
First subtract 2 revolutions from the - 840 :- (- (840-720) = -120
This gives sin -120 which is in the 3rd quadrant of the unit circle
sin -120 = - sin 60 = - sqrt3/2