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Task 25: 
You're analyzing data from a study on penguins and need to divide them into three equally sized groups based on their body mass.

Write an SQL query that selects the species, island, and body_mass_g for each penguin from the little_penguins table. Additionally, add a new column named body_mass_class that assigns each penguin to one of three groups (terciles) based on their body_mass_g, with the lightest penguins in group 1 and the heaviest in group 3.

Use SQLite syntax to write your answer. Descriptions of tables are provided in the right pane.

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Querynomicon (SQLite)

A compact database for learning the basics of SQL.

The Querynomicon database contains tables:

department - table of departments.
  • identDepartment ID.
  • nameDepartment name.
  • buildingBuilding name.
ident name building
gen Genetics Chesson
little_penguins - table of little penguins.
  • speciesPenguin species.
  • islandIsland of residence.
  • bill_length_mmBill length, mm.
  • bill_depth_mmBill depth, mm.
  • flipper_length_mmFlipper length, mm.
  • body_mass_gBody mass, g.
  • sexSex.
species island bill_length_mm bill_depth_mm flipper_length_mm body_mass_g sex
Gentoo Biscoe 52.1 17 230 5550 MALE
penguins - table of penguins.
  • speciesPenguin species.
  • islandIsland of residence.
  • bill_length_mmBill length, mm.
  • bill_depth_mmBill depth, mm.
  • flipper_length_mmFlipper length, mm.
  • body_mass_gBody mass, g.
  • sexSex.
species island bill_length_mm bill_depth_mm flipper_length_mm body_mass_g sex
Gentoo Biscoe 52.1 17 230 5550 MALE
staff - table of employees.
  • identEmployee number.
  • personalEmployee first name.
  • familyEmployee last name.
  • deptDepartment.
  • ageAge.
ident personal family dept age
7 Abram Chokshi gen 23