Original practice · fully worked
Original variant: equipment protection cooperative
An equipment protection cooperative collects an annual fee of 100 dollars per member. A member is expected to incur 0.30 sensor failures costing 80 dollars each and 0.04 power-surge failures costing 400 dollars each during the year. The cooperative reimburses the same fraction of every covered loss and wants expected surplus of 75 dollars per member, with no other expenses. Calculate that reimbursement fraction.
- A
0.250 - B
0.375 - C
0.400 - D
0.625 - E
0.750
Answer and calculation
Expected covered loss is 0.30(80)+0.04(400)=40 dollars. The surplus target leaves 25 dollars for reimbursement, so the common fraction is 25/40=0.625, choice D.
Setup
Setup
Let q denote the common fraction of each loss paid by the cooperative.
fee=100,target surplus=75 Model
Model
Add frequency times severity across the two failure sources to obtain expected covered loss.
E[L]=0.30(80)+0.04(400) Compute
Compute
Equate fee less expected reimbursement to the target surplus.
E[L]=24+16=40 100−40q=75 q=4025=0.625 Answer
Answer
The cooperative should reimburse 62.5% of every covered loss.
q=0.625(D)