In one work station, one operator is assigned to a number of automatic machines. The running time $/$machine is $0\mathrm{.}34$ minute. The operator then spends $69$ seconds to load and unload the machine as well as to pack the product into a box. The operator is paid P$40/$hour and the machine costs P$150/$hour to run. The machine needs to be loaded only once per shift. What is the best operator to machine ratio?