What pricing model is being used if a newspaper offers subscriptions of $50 for 5 users, $75 for 10 users, and $100 for 20 users?

The pricing model being utilized here is indeed graduated tiered pricing. This approach involves offering various pricing tiers based on the quantity of users that a customer wishes to include in their subscription.

In the case presented, the newspaper offers different subscription prices depending on the number of users: $50 for 5 users, $75 for 10 users, and $100 for 20 users. Each tier provides an incentive for customers to opt for a higher tier, as they get more users at a comparatively lower cost per user as they scale up. This model allows businesses to cater to different customer needs and encourages larger subscriptions by providing tiered options.

The other pricing models are fundamentally different. Flat rate pricing typically charges a single fixed price for all users or usage, without variations for different tiers or quantities. Usage-based pricing charges based on the actual usage levels, rather than offering set tiers for defined quantities. Subscription pricing, while relevant here as it describes the payment for access to a service over time, does not specifically highlight the tiered structure that is central to the correct answer. Thus, the most accurate term for the pricing model used by the newspaper is graduated tiered pricing.