1. The problem statement, all variables and given/known data This is from a practice exam: 2. Relevant equations t-distribution? 3. The attempt at a solution I feel like if I start with part (b) and fine the probability that 1 carton falls in the interval, I can then apply the binomial distribution to find the prob that 5 cartons fall in that interval. But I am very lost as to where to start. How can I calculate a t-value without a mu value? Any thoughts on this one?