Question

   Chocolate bars produced by a certain machine are labeled with 8.0 ounces. The distribution of the actual weights of these chocolate bars is Normal with a mean of 8.1 ounces and a standard deviation of 0.1 ounces. A chocolate bar is considered underweight if it weighs less than 8.0 ounces. How should the chocolate bar wrappers be labeled so that only 1% of such bars are underweight?
   
   7.77 ounces
   7.87 ounces
   8.23 ounces
   8.33 ounces

Answer 1

µ=8.1     

σ = 0.1

proportion=0.01

  

Z value at 0.01=    -2.326    (excel formula =NORMSINV(0.01) )

z=(x-µ)/σ

so, X=zσ+µ=    -2.326*0.1+8.1

X=7.87

so, answer is 7.87 ounces