Question 135562
it takes two construction workers a mean of 32 hours and a standard deviation of 2 hours to erect the Red Barn model. Assume the assembly times follow
the normal distribution.
-------------------------------------------------
a. Determine the z values for 29 and 34 hours. What percent of the garages take between 32 hours and 34 hours to erect?
 P(32 < x <34) = P(0 < z < 1)=0.3413
-------------------------------
b. What percent of the garages take between 29 hours and 34 hours to erect?
P(29 < x <34) = P (-1.5 < z < 0)=0.4332
--------------------------------------
c. What percent of the garages take 28.7 hours or less to erect?
P(0 < x < 28.7) = P(-16 < x < -1.65) = 0.0495
--------------------------------------------
d. Of the garages, 5 percent take how many hours or more to erect? 
Find the z-score associated with the upper 5%: z=1.645
Find the corresponding x-score using z=(x-u)/s
1.645 = (x-32)2
x-32 = 2*1.645
x = 3.290+32 = 35.29 hours
===============================
Cheers,
Stan H.