an assembly plant buys leather tops and soles from its suppliers. The leather tops have no color on them when bought. The assembly plant first dies the leather with colors like black, beige, brown and cream. Then it sews the colored leather tops to the soles. A shoe consists of one leather top and sole. Basically there are two operations in thebshoe plant: coloring and sewing. The activity times and set up times for these operations are given in minutes as follows: leather tops are processed and batches in the coloring stage with set up time of 80 minutes, and per unit processing time of 2 minutes/shoe. Sewing stage does not need any set of time and the per-unit processing time is 3 minutes/shoe. Assume that the demand of the process is 10 shoes/hour what is the optimal batch size in numbers of shoes?