Answer:
K=20
Step-by-step explanation:
There seem to be no randomness in the question.
At 1 per minutes the arrival rate is fixed.
Then compute the average cost for each person to give a four, adding the cost of guide and time waiting cost..
Therefore, K is the number of people hoping will show up.
Number of per minute waiting
= 1/2(K-1)K.
Tour cost 20+1/20(K-1).
Cost per guest= 20/k +1/20(K-1)
If the derivative is set to Zero
K=20