Exercise $6-49$ Static

First introduced in Los Angeles, the concept of Korean$-$style tacos sold from a catering truck has been gaining popularity nationally. This taco is an interesting mix of corn tortillas with Korean$-$style beef, garnished with onion, cilantro, and a hash of chili$-$soy$-$dressed lettuce. Suppose one such taco truck operates in the Detroit area. The owners have estimated that the daily consumption of beef is normally distributed with a mean of $24$ pounds and a standard deviation of $6$ pounds. While purchasing too much beef results in wastage, purchasing too little can disappoint customers. $[$You may find it useful to reference the $z_{?}$ table.$]$

a$.$ Determine the amount of beef the owners should buy so that it meets demand on $80\%$ of the days. $($Round your final answer to $2$ decimal places.$)$

Amount of beef

b$.$ How much should the owners buy if they want to meet demand on $95\%$ of the days? $($Round your final answer to $2$ decimal places.$)$

Amount of beef