Your supervisor asked you to conduct a survey on avocadoes sold at a national gr

Question

Your supervisor asked you to conduct a survey on avocadoes sold at a national grocery chain. In your report, you will need to construct a 93% confidence interval for the mean weight of avocadoes. Based on past surveys on avocadoes sold at this grocery chain, the standard deviation of weight is 0.67 pound. It is required that the maximum likely sampling error of mean weight be 0.10 pound. An avocado at the grocery chain is sold for $1. What is the required budget (a whole number) for avocadoes to be included in your survey sample? Hint: Round off zvalues to 5 decimal places. Refer to some Excel value lookups: * 0.050 0.070 0.965 0.975 0.995 NORM.S.INV(*) 1.64485 1.47579 1.81191 1.95996 2.57583

Explanation / Answer

Note that      
      
n = z(alpha/2)^2 s^2 / E^2      
      
where      
      
alpha/2 = (1 - confidence level)/2 =    0.035  
      
Using a table/technology,      
      
z(alpha/2) =    1.811910673  
      
Also,      
      
s = sample standard deviation =    0.67  
E = margin of error =    0.1  
      
Thus,      
      
n =    147.3747807  
      
Rounding up,      
      
n =    148  

We need 148 avocadoes, each fro $1.

Hence, need $148. [ANSWER]

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