Question 801195
The length of time a domestic flight must wait between gate departure and takeoff taxi at Boston’s Logan International Airport is approximately normally distributed with a mean of 20 minutes and a standard deviation of 5 minutes. What is the probability that a plane must wait between 18 and 24 minutes before taxiing for takeoff after leaving the gate? 
z(18) = (18-20)/5 = -0.40 
z(24) = (24-20)/5 = +0.40 
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Then::
P(18 <= x <= 24) 
= P(0.3121 <= z <= 0.2881) 
= normalcdf(-0.4,0.4) 
= 0.3108
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Cheers,
Stan H.
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