Graded Quiz on Assignment :Databases and SQL for Data Science with Python (IBM Data Analyst Professional Certificate) Answers 2025

1. Question 1

What is the total number of crimes recorded in the CRIME table?

• ✅ 533

• ❌ 555

• ❌ 433

• ❌ 53

Explanation:
Typical lab subset used in the course contains 533 rows for the CRIME table.

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2. Question 2

Correct query to list community areas (number & name) with per capita income < 11000:

• ❌ SELECT COMMUNITY_AREA_NUMBER, COMMUNITY_AREA_NAME WHERE CENSUS_DATA FROM PER_CAPITA_INCOME<11000

• ❌ SELECT COMMUNITY AREA NUMBER, COMMUNITY_AREA_NAME FROM CENSUS_DATA WHERE PER_CAPITA_INCOME<11000 (invalid column spacing)

• ✅ SELECT COMMUNITY_AREA_NUMBER, COMMUNITY_AREA_NAME FROM CENSUS_DATA WHERE PER_CAPITA_INCOME<11000

• ❌ ... WHERE PER_CAPITA_INCOME>11000

Explanation:
Third option has correct SELECT ... FROM ... WHERE syntax and correct column names.

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3. Question 3

When you list all case numbers for crimes involving a minor, how many rows are retrieved?

• ❌ 3

• ✅ 4

• ❌ 2

• ❌ 1

Explanation:
In the lab dataset the filter for crimes involving a minor returns 4 case numbers.

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4. Question 4

Query to identify kidnapping crimes involving a child:

• ❌ WHERE PRIMARY_TYPE = "KIDNAPPING" (too broad)

• ✅ WHERE PRIMARY_TYPE = "KIDNAPPING" AND DESCRIPTION LIKE "%CHILD%"

• ❌ WHERE DESCRIPTION LIKE "%CHILD%" (may miss records labeled as kidnapping without the word child)

• ❌ AND DESCRIPTION = “%CHILD%” (invalid use of = with wildcard)

Explanation:
Correct approach: filter primary type and use LIKE '%CHILD%' to catch DESCRIPTION text mentioning child.

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5. Question 5

Which two clauses were used to get the unique list of crime types recorded in schools?

• ❌ COUNT

• ❌ AVERAGE

• ✅ DISTINCT

• ✅ LIKE

Explanation:
You’d use DISTINCT to get unique crime types and LIKE in the WHERE clause (e.g. LOCATION_DESCRIPTION LIKE '%SCHOOL%') to limit to school locations.

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6. Question 6

What was the average safety score for middle schools?

• ❌ 46.42

• ❌ 49.52

• ✅ 49.62

• ❌ 48.0

Explanation:
Lab summary shows the mean safety score for middle schools as 49.62.

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7. Question 7

What to add to list five community areas with highest % households below poverty?

• ❌ ORDER BY PERCENT_HOUSEHOLDS_BELOW_POVERTY LIMIT 5 (missing DESC)

• ❌ ORDER BY PERCENT_HOUSEHOLDS_BELOW_POVERTY DESC LIMIT (missing limit value)

• ❌ ORDER BY PERCENT_HOUSEHOLDS_BELOW_POVERTY DESC (missing LIMIT)

• ✅ ORDER BY PERCENT_HOUSEHOLDS_BELOW_POVERTY DESC LIMIT 5

Explanation:
Sort descending and limit to 5: ORDER BY ... DESC LIMIT 5.

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8. Question 8

Which community area number has the most criminal incidents?

• ❌ 36.0

• ✅ 25.0

• ❌ 20.0

• ❌ 23.0

Explanation:
In the lab dataset community area 25.0 (Austin) has the highest count of incidents.

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9. Question 9

Correct sub-query to find the community area name with the highest hardship index:

• ❌ ... WHERE HARDSHIP_INDEX IN (SELECT MOST(HARDSHIP_INDEX)...) (MOST not valid)

• ❌ ... WHERE HARDSHIP_INDEX AS (SELECT MAX(...)) (invalid syntax)

• ✅ SELECT COMMUNITY_AREA_NAME FROM CENSUS_DATA WHERE HARDSHIP_INDEX IN (SELECT MAX(HARDSHIP_INDEX) FROM CENSUS_DATA);

• ❌ incomplete/invalid option

Explanation:
Use MAX(...) in a subquery and match HARDSHIP_INDEX to that value.

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10. Question 10

What is the name of the community with the most number of crimes?

• ❌ Englewood

• ✅ Austin

• ❌ Riverdale

• ❌ Fuller Park

Explanation:
Based on the lab subset, Austin (community area 25) has the largest number of crimes.

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🧾 Summary Table

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