Kakak kakak sekalian, saya ada soal yang tidak saya mengerti,

Batches of containers arrive at a stockyard according to a Poisson process with a rate
of λ = 15 batches per day. Each batch consists of two or three containers with respective
probabilities of 23
and 13
. The stockyard has space for only 50 containers. An arriving batch
finding not enough space is lost and is brought elsewhere. Containers from the same batch
are removed simultaneously after a random time. The holding times of the batches are
independent random variables and have a lognormal distribution with a mean of 1 day and
a standard deviation of 2 days for batches of size 3 and a mean of 1 day and a standard
deviation of 12
day for batches of size 3. Calculate the long-run fraction of batches of size
2 that are lost and the long-run fraction of batches of size 3 that are lost.

soal di atas menggunakan sistem antrian apa? kedatangannya kan berkelompok, lalu pelayanannya berdasarkan distribusi lognormal itu kah?