Ad auction eCPM by campaign — PANDAS practice

groupbyderived metrics

The full problem statement is available to Pro members.

preloaded fixtures

import pandas as pd

ad_auctions = pd.DataFrame({
    "campaign": ["brand-a", "brand-a", "brand-b", "brand-b", "brand-c", "brand-c"],
    "device": ["mobile", "desktop", "mobile", "desktop", "mobile", "desktop"],
    "impressions": [120000, 40000, 25000, 15000, 90000, 10000],
    "cost": [960.0, 520.0, 300.0, 240.0, 450.0, 130.0],
    "conversions": [240, 130, 40, 36, 90, 12],
})

Guest mode · solve history stays on this device; code isn’t saved. Sign in to save future work

Pro problem

“Ad auction eCPM by campaign”

This is one of the real interview questions in Pro. Try Pro free for 7 days to unlock it and everything below:

293 interview-grade problems across SQL, Python & pandas
104+ real-world SQL problems: SaaS retention, fintech ledgers, supply chain, recursive CTEs
18 company interview packs (Amazon, Meta, Google, Uber and more)
AI "explain my mistake" tutor and mock interviews
Use QueryLab inside Claude, Cursor & other AI assistants

// built for real interview rounds

Practice the patterns 18 top companies test

329 problems · 36 free forever · 293 unlocked with Pro

Start 7-day free trial · $0 today see plans ($12/mo or $99/yr) →

Card required. Then $12/month. Cancel before your trial ends and you pay nothing.

or keep practicing free problems →

Secure checkout by Paddle · instant access · cancel anytime from your account