DIT Intern Hiring Test - MongoDB and Programming Fundamentals (MCQ Set)

This set is from the DIT intern hiring online assessment. It mixes a Python loop-tracing question, a system-design scenario question on integrating a smart city platform, and four MongoDB questions covering database and collection creation, query output with sorting and limiting, index selection for query optimization, and general query-method behaviour.

Unless a question says otherwise, pick exactly one option.

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Question 1 - Value of 'a' at the End of the Loop

What is the value of a at the end of the loop?

a = 0
for b in range(0,10,2):
    a += b + 1

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Question 2 - Integration Optimization

In a smart city project, the system manages various functions like urban services, autonomous vehicles, drone deliveries, health monitoring, and AI-driven crime prediction. Traffic management covers both vehicles and drones. There are also energy tracking features, including charging stations for electric vehicles and drones. The emergency system predicts future crises using AI and utilizes health data from wearables.

Challenges introduced by this setup include:

Varying data flow rates
Mixed data structures, including structured and unstructured data
Different data criticality levels, with some requiring immediate processing and others

needing periodic analysis

Considering these complexities and the city's goals of integration, reliability, and adaptability, which optimization ...

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Question 3 - Optimization

Millions of documents are inserted into the customers collection in MongoDB. Each document has the following structure.

{"_id": 1, "Name":{"First Name":"Adam", "Last Name":"Grant"}, "Age": 20}

An index is created on the customers collection as follows.

db.customers.createIndex( { "Name.Last Name" : 1}, { name: "LastNameIndex"} )

Consider the query shown below.

db.customers.find({
    "Name.Last Name" : "Thom"
}, {
    "_id" : NumberInt(0),
    "Name.First Name" : NumberInt(1),
    "Name.Last Name" : NumberInt(1)
}).sort({
    "Name.Last Name" : NumberInt(1)
});

Which of the following indexes will improve the query execution time?

Pick ONE option.

A. db.customers.createIndex( { "Name.First Name" : 1, "Name.Last Name": 1}, { name: "FirstNameCompoundIndex"} )
B. db.customers.createIndex( { "Name.Last Name" : 1, "Name.First Name": 1}, { name: "LastNameCompoundIndex"} )
C. db.customers.createIndex( { "Name.First Name" : 1}, { name: "FirstNameIndex"} )
D. All of the above.

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Question 4 - Create DB and Collection

Which MongoDB command is used to create a new database and a collection within that database?

Pick ONE option.

A. use myDatabase; db.createCollection('myCollection');
B. db.newDatabase('myDatabase').newCollection('myCollection');
C. connect('myDatabase'); addCollection('myCollection');
D. db.myDatabase.insert({collection: 'myCollection'});

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Question 5 - Limiting Query with Sort

The following documents are inserted into a newly created people collection in MongoDB.

db.people.insertMany([{ "_id" : 1, "name" : "Adam", "age" : 23, "job" : "painter" },
{ "_id" : 2, "name" : "John", "age" : 45, "job" : "driver" },
{ "_id" : 3, "name" : "Jake", "age" : 21, "job" : "director" },
{ "_id" : 4, "name" : "Paul", "age" : 35, "job" : "writer" },
{ "_id" : 5, "name" : "Laura", "age" : 33, "job" : "doctor" },
{ "_id" : 6, "name" : "Ram", "age" : 56, "job" : "gardener" }])

What will be the output of the following query?

db.people.find({age: {$gte: 35}}).limit(2).sort({job:1, name: 1})

Pick ONE option.

A. `` { "_id" : 2, "name" : "John", "age" : 45, "job" : "driver" } { "_id" : 4, "name" : "Paul", "age" : 35, "job" : "writer" } ``
B. `` { "_id" : 6, "name" : "Ram", "age" : 56, "job" : "gardener" } { "_id" : 4, "name" : "Paul", "age" : 35, "job" : "writer" } ``
C. `` { "_id" : 4, "name" : "Paul", "age" : 35, "job" : "writer" } { "_id" : 6, "name" : "Ram", "age" : 56, "job" : "gardener" } ``
D. `` { "_id" : 2, "name" : "John", "age" : 45, "job" : "driver" } { "_id" : 6, "name" : "Ram", "age" : 56, "job" : "gardener" } ``

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Question 6 - MongoDB: Queries

Which of the following statements are incorrect?

Pick ONE or MORE options.

A. db.collection.findAndModify() does not have any way to allow creation of new documents if it does not already exist.
B. db.orders.countDocuments( {}, { limit: 100, skip: 25 } ) will return 100 orders after skipping the first 25 documents in the collection.
C. db.collection.findOneAndReplace() is not a valid MongoDB Collection method.
D. db.products.remove( { qty: { $gt: 20 } }) will remove all the products from the collection having the qty value greater than equal to 20.