+36915 The packs are SUPPOSED to weigh 250 gms
The ACTUAL weight mean is 255 gm with S.D. 2.5 gm
How many % weigh LESS than 250? 255 - 250 = 5 gm this is 5gm / 2.5 gm = 2 standard deviations BELOW the mean z score = -2
From a z -score table :.0228 is the fraction that is -2 standard deviations below the mean
.0228 = 2.28% are leass than 250 gm
