Calculating products made within a certain amount of time I have an interesting question that I'm having a hard time figuring out how to diagram/solve. 
The problem is about a product's process cycle. So the amount of steps it takes to make said product and how much time each step of the process takes. Steps are done 1-6 in order (you can't jump around). When a product finishes Step 1 a second product can then move into Step 1 but cannot move into Step 2 until the first product is done that step. The steps all have different times. The question is how many products can be produced in one hour. It'd be great to see a simple formula for this, Thanks!
Step 1: 15 seconds
Step 2: 30 seconds
Step 3: 60 seconds
Step 4: 40 seconds
Step 5: 20 seconds 
Step 6: 30 seconds

Let $a=(15,30,60,40,20,30)$,  $d_{max}=\max(a)=60$.
Then the first product is finished at time $\sum a=195$ s.
After that, each product is finished with delay $d_{max}=60s$, thus at $255$, $315$, $\ldots$
So solving $195+60(n-1)\le3600$ in $\mathbb{N}$ would result in the maximum $n=57$, which is the final number of products.
