Independent solution

How to solve this Exponential Distribution question

Setup

Setup

Write the ordinary-deductible payment as a positive-part transformation of the loss.

Y=(X1)+Y=(X-1)_+
Pr(Y=0)=Pr(X1)=1e1/4=0.2212<0.5\Pr(Y=0)=\Pr(X\le1)=1-e^{-1/4}=0.2212<0.5

Model

Model

For a positive candidate median y, the event Y at most y is the same as X at most y+1.

Pr(Yy)=Pr(Xy+1)=1e(y+1)/4\Pr(Y\le y)=\Pr(X\le y+1)=1-e^{-(y+1)/4}

Compute

Compute

Set the payment distribution function equal to one half and solve.

1e(m+1)/4=0.51-e^{-(m+1)/4}=0.5
m=4ln21=1.7725887m=4\ln2-1=1.7725887

Answer

Answer

The median payment rounds to 1.77.

1.77(A)\boxed{1.77\quad\text{(A)}}