A minor component is to be added to a powdered food product at $4\%$ by mass. The

product specification requires that there be a $99\%$ probability that each $250-g$ packet

contains between $9\mathrm{.}5$ and $10\mathrm{.}5g$ of the additive. The variance in the mass fraction of the

minor component as a function of time was determined by removing samples from the

mixer. Determine the mixing time from the following data.

This involves the food process engineering principles of mixing. Will upvote correct answer!