sample size?

at a plant the productionrates vary with a mean of 0.84 and a standard deviation of 0.01. a line supervisor confirmed that the production rate variation follows a normal distribution. a plant wants to produce a batch of parts and wants to be 99% sure that they will have X good parts in the end. How many parts shall they begin with? Only one batch can be runned.

Are you stating the problem as-is or are you paraphrasing? This problem doesn't really make sense. Production rate usually refers to the number of objects that you produce in a given time. Part of the problem is talking about rate of production and the other is talking about defective rates. And what does it mean to have a normally distributed non-defective rate of 0.84 with a standard deviation of 0.01? You could say that the non-defective rate of producing N items is normally distributed with mean 0.84 with a standard deviation of 0.01. But then we would need to know that number N.