Every day, Angela gets a boba drink from Asha in Berkeley. She believes the machine that's used to add the boba pearls to the drink is calibrated to put an exact amount of boba in each drink, with some variability due to chance. To get a sense of how the amount of boba in a drink varies, Angela plans to randomly sample customers throughout November and record the weight (in grams) of the boba pearls in each customer's drink. Suppose that Angela wants to use her sample to create a 68% confidence interval for the true population median of boba weight per drink and she knows that the population SD is 2 grams. What is the minimum sample size she needs to create a confidence interval that has a width of 0.4 grams?