Question 1050446
a) z = invNorm(.16)-.9945 Use Your TI
{{{z =blue (x - mu)/blue(sigma)}}}
0r
 {{{blue(sigma)*z + mu=blue (x)}}}
 {{{1*-.9945 + 19 = 18.0054}}} = 18days
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b middle 97%:  from .015 to .985 {{{(100-.97)/2 = .015}}}
z = invNorm( 98.5)= 2.17 and invNorm(.015)= -2.17
 P(-2.17 ≤ z ≤ 2.17).
TI syntax is normalcdf(smaller z, larger z) 
P(-2.17 ≤ z ≤ 2.17) = normalcdf(-2.17, 2.17) Use Your TI