12.4. In manufacture of lamps, the clearance wxy is of interest, where xdistance from rim of base...

12.4. In manufacture of lamps, the clearance w¼xy is of interest, where x¼distance from rim of base to the glass,

and y¼distance from rim of base to top of inner shell. For x’s, large samples gave estimated m¼1.0499, s¼ 0.0428 in., whereas for y’s m¼0.9079, s¼0.0120 in. Good normality was present. Describe the distribution of w¼xy. What percentage of w’s are negative in random assembly?