This Exam P sample reference tests Deductible Payments. A deductible between 60 and 200 removes the smallest claim and reduces the other two payments dollar for dollar. Setting the resulting expected payment 40-0.06d equal to 30 gives d=166.67, choice C.
These notes identify the calculation error associated with each wrong letter when that error is reproducible.
AAt a deductible of 100, the expected payment is 0.05(100)+0.01(2900)=34, not 30.
BFor deductibles from 100 up to but not including 150, the expected payment decreases from 34 toward 31 and never reaches 30.
DFor deductibles from 200 to 250, only the largest loss pays; the expected payment ranges from 28 down to 27.5, already below the target.
EAt deductibles of at least 250, the expected payment is no greater than 27.5 and continues to decrease.
Original practice · fully worked
Original variant: calibrate an exponential deductible
A repair cost follows an exponential distribution with mean 1000. A plan pays the amount of each repair cost above an ordinary deductible d, with no upper limit. Determine d if the expected plan payment per repair is 300.
A 300
B 700
C 1204
D 2303
E 3333
Variant answer in brief
For an exponential cost with mean 1000, the expected excess over d is 1000 exp(-d/1000). Equating this to 300 gives d=1203.97, choice C.
Setup
Setup
Use the exponential survival function to express the expected excess payment.
Pr(X>x)=e−x/1000
E[(X−d)+]=∫d∞Pr(X>x)dx
Model
Model
Evaluate the tail integral and set it equal to the target payment.
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