Estimation question

Estimate the cost of storing Google Photos on the photos app.

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Estimation combining total photo volume, storage cost per gigabyte, and scale of a specific product.

Estimate total users and average storage used per user, for example 1 billion users averaging 10 gigabytes stored each.
Compute total storage volume, 1 billion times 10 gigabytes gives 10 exabytes of stored data.
Estimate cost per gigabyte of cloud storage at this scale, much lower than consumer cloud pricing due to infrastructure efficiency, a few cents per gigabyte a year.
Multiply total storage by cost per gigabyte to estimate total annual storage cost.
State the result as a range and note this excludes compute costs like image indexing and search.

Breaks the estimate into total data volume first, then applies a cost per gigabyte figure specific to large scale infrastructure, not retail pricing.
Shows the math, 10 exabytes times an assumed cost per gigabyte a year gives roughly $200 million a year, clearly marked as a rough assumption.
Notes the estimate excludes related costs like deduplication, compression, and machine learning processing for photo search.

Using consumer cloud storage retail prices instead of internal infrastructure cost, which is far lower.
Not estimating total data volume first before applying a cost rate.
Ignoring that deduplication and compression likely reduce the effective stored volume.

How would deduplication and compression change this estimate?
How would you separate storage cost from the cost of running photo search and facial recognition?