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According to the U.S. Department of Labor, the average American household spends

ID: 3132197 • Letter: A

Question

According to the U.S. Department of Labor, the average American household spends $639 on household supplies per year. Suppose annual expenditures on household supplies per household are uniformly distributed between the values of $257 and $1,021. What is the standard deviation of this distribution? What is the height of this distribution? What proportion of households spend more than $890 per year on household supplies? What proportion of households spend more than $1,210 per year on household supplies? What proportion of households spend between $350 and $470 on household supplies? (Round your answers to 4 decimal place.) Standard deviation = Height = P(x > 890) = P(x > 1,210) = P(350

Explanation / Answer

a)

Note that here,          
          
a = lower fence of the distribution =    257      
b = upper fence of the distribution =    1021      
          
Hence,

s^2 = variance = (b -a)^2 / 12 =    48641.33333  

Thus,

  
s = standard deviation = sqrt(s^2) =    220.5478028 [ANSWER]

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b)

h = 1/(b-a) = 1/(1021-257) = 0.001308901 [ANSWER]

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c)

Note that here,          
          
a = lower fence of the distribution =    257      
b = upper fence of the distribution =    1021      
          
          
Note that P(x>c) = P(c<x<b) = (b-c)/(b-a). Thus, as          
          
c = critical value =    890      
          
Then          
          
P(x>c) =    0.171465969   [ANSWER]

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d)

As the distribution is only from 257 to 1021, then it could no way be >1210.

Hence,

P(x>1210) = 0 [ANSWER]

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E)

Note that here,          
          
a = lower fence of the distribution =    257      
b = upper fence of the distribution =    1021      
          
Thus, the area between the said numbers is          
          
c = lower number =    350      
d = higher number =    470      
          
Thus, the probability between these two values is          
          
P = (d - c)/(b - a) =    0.157068063   [ANSWER]  
  

      

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