A well-known maker of jams and jellies packages its jams in jars
labeled “250 mL”. The process used to fill the jars is known to
dispense an amount of jam that is a Normally distributed variable
with μ = 252 mL and σ = 0.9 mL.. If changing σ while keeping μ the
same were possible for this process, what should σ be set at so
that the percentage of jars filled with less than 250 mL will be at
most 0.2%?