Question 1197724
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Hi  
 Normal Distribution: µ = 120mm and σ = 10mm  
Smallest 15% to be given away.
What is the cut-off diameter

Using TI or similarly an inexpensive calculator like an Casio fx-115 ES plus
Invnorm(.15) =  -1.0364
{{{blue(sigma)*z + mu =blue (x)}}}  10*(-1.0364) + 120 = 109.636mm 
Nearest whole number, cut-off diameter = 110mm
Wish You the Best in your Studies.
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