Find the Probability That Two Uniform Variables Have Product Above One-Half
Company: Squarepoint
Role: Data Scientist
Category: Statistics & Math
Difficulty: medium
Interview Round: Technical Screen
Let `X` and `Y` be independent random variables, each uniformly distributed on the interval `(0, 1)`. What is the probability that `X * Y > 1/2`?
### Constraints and Clarifications
Use the continuous uniform distribution and the given independence. Explain the relevant region or conditional probability and give an exact expression. The distinction between strict and non-strict inequality at the boundary has probability zero here.
```hint Locate the feasible part of the square
For a fixed value of `X`, determine which values of `Y` can satisfy the product inequality and when that interval is nonempty.
```
### What a Strong Answer Covers
- The uniform joint density on the unit square and the product-inequality region.
- Correct integration limits rather than integrating over impossible values of `X`.
- An exact probability, a reasonable numerical interpretation, and a simple bound that checks the result.
### Follow-up Questions
1. How does the expression change for `P(X * Y > t)` with `0 < t < 1`?
2. Why is multiplying `P(X > 1/2)` and `P(Y > 1/2)` not the answer to the original question?
Overview: Compute the probability that two independent uniform variables have product above one-half by conditioning or integrating over the unit square.
Find the Probability That Two Uniform Variables Have Product Above One-Half
Squarepoint
Sep 9, 2026
mediumData ScientistTechnical ScreenStatistics & Math
1
0
Let X and Y be independent random variables, each uniformly distributed on the interval (0, 1). What is the probability that X * Y > 1/2?
Constraints and Clarifications
Use the continuous uniform distribution and the given independence. Explain the relevant region or conditional probability and give an exact expression. The distinction between strict and non-strict inequality at the boundary has probability zero here.
What a Strong Answer Covers Guidance
The uniform joint density on the unit square and the product-inequality region.
Correct integration limits rather than integrating over impossible values of
X
.
An exact probability, a reasonable numerical interpretation, and a simple bound that checks the result.
Follow-up Questions Guidance
How does the expression change for
P(X * Y > t)
with
0 < t < 1
?
Why is multiplying
P(X > 1/2)
and
P(Y > 1/2)
not the answer to the original question?