9.4.1 Consider the two-server overflow queue of Section 9.4.4 and suppose the arrival rate is  D 10 per hour. The two servers have rates 6 and 4 per hour. Recommend which server should be placed first. That is, choose between

1 D 6;

2 D 4 and

1 D 4;

2 D 6;

and justify your answer. Be explicit about your criterion.