Calculate break-even new customers for a 30% Rent-a-Home discount
Company: Capital One
Role: Data Scientist
Category: Statistics & Math
Difficulty: medium
Interview Round: Technical Screen
##### Question
Capital One (C1) is evaluating a promotional offer on its Rent-a-Home (RH) product and wants you to size the unit economics.
**Base assumptions**
- C1 has 2,000,000 active cardholders.
- Currently 5% use Rent-a-Home (RH) annually.
- Average RH spend per RH user per year is $500.
- A proposed promo gives 30% off RH spend, fully funded by C1.
- Average first-year net revenue per new cardholder (after non-RH rewards, servicing, and expected credit loss) is $550.
- Ignore interchange on RH transactions for simplicity.
Let **x** = the number of new customers acquired because of the promo.
1. **Base break-even.** Write the break-even equation where incremental revenue from the new customers equals the promo cost across existing RH users plus new RH users, then solve for **x**. Show your work and final numbers.
2. **Sizing and realism.** Express **x** as a percentage of the 2,000,000 base, and discuss whether this target is realistic given typical acquisition funnels and approval rates.
3. **Spend-uplift extension.** Now extend the scenario and assume that during the promo: (i) existing RH users increase RH spend by 20% (from $500 to $600); (ii) new customers who join because of the promo spend twice as much on RH as existing users during the promo period (i.e., $1,000). The discount remains 30% on RH spend and average first-year net revenue per new cardholder remains $550. Write and solve the break-even equation:
`550·x − 0.30·(1,000·x + 2,000,000·5%·600) = 0`
4. **Compare and explain.** Compare the new break-even **x** from part 3 to the original break-even from part 1, and explain intuitively why the required new-customer count changes despite the higher spend.
Quick Answer: A Capital One data-scientist technical screen on break-even and unit economics for a 30%-off Rent-a-Home promotion. You set up and solve the break-even equation for incremental new customers, size it against the 2M cardholder base, then re-solve under spend-uplift assumptions and explain why the required count nearly doubles.