Independent solution

How to solve this Continuous Distributions question

Setup

Setup

Determine the density constant C by requiring the density to integrate to one over its support.

1=C040(10+x)2dx=C(110150)1=C\int_0^{40}(10+x)^{-2}\,dx=C\left(\frac1{10}-\frac1{50}\right)

Model

Model

Evaluating the normalization integral gives C=12.5.

C=12.5C=12.5

Compute

Compute

Integrate the normalized density from zero to six; the resulting probability is 0.46875.

Pr(X<6)=12.5(110116)=0.46875\Pr(X<6)=12.5\left(\frac1{10}-\frac1{16}\right)=0.46875

Answer

Answer

The probability that X is below six rounds to 0.47, corresponding to choice C.

0.47(C)\boxed{0.47\quad\text{(C)}}