Answer:
a) NORM.S.INV(0.975)
Step-by-step explanation:
1) Some definitions 
The standard normal distribution is a particular case of the normal distribution. The parameters for this distribution are: the mean is zero and the standard deviation of one. The random variable for this distribution is called Z score or Z value.
NORM.S.INV Excel function "is used to find out or to calculate the inverse normal cumulative distribution for a given probability value"
The function returns the inverse of the standard normal cumulative distribution(a z value). Since uses the normal standard distribution by default the mean is zero and the standard deviation is one.
2) Solution for the problem
Based on this definition and analyzing the question :"Which of the following functions computes a value such that 2.5% of the area under the standard normal distribution lies in the upper tail defined by this value?".
We are looking for a Z value that accumulates 0.975 or 0.975% of the area on the left and by properties since the total area below the curve of any probability distribution is 1, then the area to the right of this value would be 0.025 or 2.5%.
So for this case the correct function to use is: NORM.S.INV(0.975)
And the result after use this function is 1.96. And we can check the answer if we look the picture attached. 
 
        
             
        
        
        
Answer: -n-4
Step-by-step explanation:
Distribute the - to n and 4
 
        
             
        
        
        
Answer:
5 nights
Step-by-step explanation:
Solve the inequality:
90x + 90(0.1)x + 12x + 30 
 600
Add like terms:
102x + 30 + 90(0.1)x 
 600
Isolate the variables:
102x + 90(0.1)x 
 570
102x + 9x 
 570
111x 
 570
x 
 5.13
So, the Lincolns can stay for 5 nights without exceeding $600
 
        
             
        
        
        
Answer:
The number of coins to make 6440 mm diameter is 230
Step-by-step explanation:
The diameter of the coin is 28mm
Number of coins to have 6440 mm will be
6440/28
= 230