Question 878490
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Hi
Population: mean = 21,600, Sd = 1000
a) P(x > 23,450) = 1 - P(x &#8804; 23,450) = 1 - P(z &#8804; (23450-21600)/1000) 
                                  = 1 - P(z &#8804; 1.85) = 1- .9678 = .0322 0r 3.22%
TI syntax is normalcdf(smaller, larger, µ, &#963;).
Using TI:  1 - normalcdf(-9999, 23450, 21600, 1000)
Note: The Placeholder -9999 is used as the smaller value to be at least 5 standard deviations from the mean.
b) Since this is a continuous function, we have <u> P(x < 21290) = P(x &#8804; 21290)</u>.
P(21290 &#8804; x &#8804; 21460) = normalcdf(-9999. 21460, 21600, 1000) - normalcdf(-9999. 21290, 21600, 1000)
c) P(19950 &#8804; x &#8804; 21470)= normalcdf(-9999. 21470, 21600, 1000) - normalcdf(-9999. 19950, 21600, 1000)