Solution

ID: past-exam-of-the-probability-course-of-the-university-of-oxford/2017/1/a/iii/solution

Put . The independent pair has the same joint distribution as from part (ii), because both first coordinates are uniform and independent of the same sum law. Hence
Consequently
The rate is one. This multiplication identity is the mechanism behind the exponential invariant law of a random affine recursion.

New to topics? Read the docs here!