In: Statistics and Probability
Given the following hypothesis test:
“It is believed that the mean amount of water per day that the
Gondorans drink is L liters. A random sample of 36 Gondorans is
observed. The average amount of water they drink per day is 1.62
liters, with a standard deviation of 0.4 liters. Is the mean amount
of water that Gondorans drink less than L liters? Test with α =
0.025.”
What is the biggest possible value of L (rounded to two digits
after the decimal point) so that the null hypothesis is still
retained?
L = ___________________
Ho :   µ =   1.75  
           
   
Ha :   µ <   1.75  
    (Left tail test)      
   
          
           
   
Level of Significance ,    α =   
0.03          
       
sample std dev ,    s =    0.4000  
           
   
Sample Size ,   n =    36  
           
   
Sample Mean,    x̅ =   1.6200  
           
   
          
           
   
degree of freedom=   DF=n-1=   35  
           
   
          
           
   
Standard Error , SE = s/√n =   0.4000   / √
   36   =   0.0667  
   
t-test statistic= (x̅ - µ )/SE = (   1.620  
-   1.75   ) /    0.0667  
=   -1.95
          
           
   
critical t value, t* =       
-2.0301   [Excel formula =t.inv(α/no. of tails,df)
]          
   
          
           
   
p-Value   =   0.0296   [Excel formula
=t.dist(t-stat,df) ]      
       
Decision:   p-value>α, Do not reject null hypothesis
          
           
L = 1.75
THANKS
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