My thought pattern for answering this Google estimation interview question.

Clarification:

–       Would it be correct to assume daily? Assume daily

–       Would this be Fedex ground, express, priority or total deliveries? Assume Total deliveries

Considerations:

Assume that the delivery is responsible for last-mile only.

–       No Long drone Flights

–       Average drone flight time is 30 mins max round trip

o   All deliveries must be within 15 mins of the source facility

–       The average weight of a fedex package is 15-25 pounds

o   The average weight drones can carry is 5 pounds

§  Packages to be delivered must be 5 pounds or below

o   Clarification on what “all” means? “All” packages that meet the weight requirements can be delivered via drone

§  This also assumes each package can be flown on a done based on size: (Length/Width)

–       All drone deliveries do not have signatures requirements

Calculations:

Total Global daily FedEx deliveries = 18M

–       US is FedEx largest market with the USPS making up the bulk of its business:

o   Assume US consumes 80% of total deliveries

The number of packages in the US being delivered daily:

18M*80%=14.1M

Since average packages are 15-25lbs in weight, assume the drone delivery addressable market is less:

For the sake of the exercise, the percentage of packages that are 5lbs or and below are 30%

The number of packages FedEx delivers that 5lbs and below:

14.1M*30% = 4.23M

Drone Deliveries (Per Hour)

–       Assuming a 12-hour window for delivery 8am-8pm

–       Average drone flight time (Batery): 30 Mins (15 mins to drop, 15 mins return)

–       Time to recharge each drone = 90 mins

–       The number of packages delivered per hour: 4.23M/12

o   = 352,500 per hour for 12 hours

The total amount of drones needed are based on 2 scenarios:

–       Perfect scenario: All drones deliver and return on time with no issues or breakages:

o   An available drone to delivery per hour: (1 drone delivering, 1 drone charging) = 352,500*2 = 705,000 Drones

–       Realistic Scenario – to account for potential drone delivery/return, battery and breakage problems – we should account for 15% overage to ensure each drone leaves at the top of the hour.

o   = 705,000 + (352,500*15%) = 705,000 + 52,875 = 757,875K Drones