Exploratory Data Analysis using SQL :Applied Data Science Capstone (Applied Data Science Specialization) Answers 2025

Question 1

Which of the following will retrieve up to 20 records from the spacex table?

• ❌ SELECT TOP 20 rows from SPACEXTBL

• ❌ SELECT * from SPACEXTBL where count(*)=20

• ❌ SELECT * from SPACEXTBL MAX 20

• ✅ SELECT * from SPACEXTBL LIMIT 20

Explanation: LIMIT 20 is the correct SQL clause (MySQL/Postgres/SQLite) to return up to 20 rows.

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Question 2

Which of the following queries display the minimum payload mass?

• ✅ select min(payload_mass__kg_) from SPACEXTBL

• ❌ select payload_mass__kg_ from SPACEXTBL order by payload_mass__kg_ desc LIMIT 1

• ❌ select payload_mass__kg_ from SPACEXTBL where payload_mass__kg_=(select max(payload_mass__kg_) from SPACEXTBL) LIMIT 1

• ❌ select payload_mass__kg_ from SPACEXTBL order by payload_mass__kg_ group by booster_version LIMIT 1

Explanation: MIN() returns the minimum value directly; the others either return the maximum or are incorrectly formed.

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Question 3

Which query gives total payload mass in a column named Total_Payload_Mass?

• ❌ SELECT sum(PAYLOAD_MASS__KG_) from SPACEXTBL

• ❌ SELECT count(PAYLOAD_MASS__KG_) as Total_Payload_Mass from SPACEXTBL

• ✅ SELECT sum(PAYLOAD_MASS__KG_) as Total_Payload_Mass from SPACEXTBL

Explanation: SUM(...) AS Total_Payload_Mass computes the total and names the result column as required.

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Question 4

Which query displays mission outcome counts for each launch site?

• ✅ select count("Mission_Outcome") as MISSION_OUTCOME_COUNT,Launch_Site from SPACEXTBL group by "Launch_Site";

• ❌ select sum("Mission_Outcome") as MISSION_OUTCOME_COUNT,Launch_Site from SPACEXTBL group by "Launch_Site";

Explanation: COUNT() gives counts per launch site. SUM() would add numeric values (only valid if Mission_Outcome is numeric and you wanted the sum).

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Question 5

What are the unique launch sites mentioned in the Spacex table?

• ❌ None of the Above

• ❌ CCAFS LC-40,KSC LC-39B,VAFB SLC-4k , CCAFS SLC-40

• ❌ CCAS LC-40,KSC LC-39A,VAFB SLC-4E , CCAFS SLC-80

• ✅ CCAFS LC-40,KSC LC-39A, VAFB SLC-4E , CCAFS SLC-40

Explanation: The list with KSC LC-39A and VAFB SLC-4E matches the typical dataset site names; the other options contain typos or incorrect site identifiers.

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