CompTIA DA0-001 - CompTIA Data+ Certification Exam

In SQL, the functions:

MIN() – returns the minimum value in a set

SUM() – returns the total sum of a numeric column

COUNT() – returns the number of rows (or non-NULL values)

These are all classic aggregate functions, because they:

Take multiple rows as input

Return a single summary value per group (or per table if no GROUP BY is used)

Other categories:

Logical is usually associated with conditions (e.g., AND, OR, NOT), not MIN/SUM/COUNT.

Filtering is done with WHERE or HAVING clauses, not MIN/SUM/COUNT themselves.

System functions typically provide system metadata, timestamps, or environment info (e.g., current user, server name).

Therefore, functions like MIN, SUM, and COUNT are Aggregate functions (A).

CompTIA Data+ Reference (concept alignment):

CompTIA Data+ Official Exam Objectives – Domain on Data Manipulation (using aggregate functions such as COUNT, SUM, MIN, MAX, AVG).

CompTIA Data+ Official Study Guide – SQL section that explicitly lists aggregate functions and their usage in queries.

A derived variable is created through mathematical computations or transformations from existing data. In this case, "income per day" is derived by combining multiple existing variables​.

Explanation

Normalization is the process of reorganizing data in a database so that it meets two basic requirements: There is no redundancy of data, all data is stored in only one place. Data dependencies are logical, all related data items are stored together.

Put simply, data normalization ensures that your data looks, reads, and can be utilized the same way across all of the records in your customer database. This is done by standardizing the formats of specific fields and records within your customer database.

A word cloud is an ideal choice for visualizing what employees are searching for on an intranet site. It represents the frequency of word occurrence in a visually impactful way, withmore commonly searched terms appearing larger in the cloud. This allows for quick identification of the most popular queries and topics of interest among employees. Unlike histograms, pie charts, or scatter plots, word clouds can effectively display textual data, which is the nature of search queries. They are particularly useful for analyzing text data from surveys or feedback forms, which can be similar to search query data in an intranet environment1234.

Before merging (joining) two datasets, it is crucial to ensure that theunits of measurement are consistentto maintain accuracy and comparability. This process is callednormalization.

Option A (Blend):Incorrect. Blending is used to combine data from multiple sources but does not standardize unit measurements.

Option B (Reduce):Incorrect. Reducing data refers to filtering or aggregating data, which does not address unit inconsistencies.

Option C (Concatenate):Incorrect. Concatenation combines datasets without standardizing units, leading to inconsistent data.

Option D (Normalize):Correct.Normalization ensures that all values in a dataset are converted to a common scale (e.g., converting kilograms to pounds) before performing operations like joins.

In this dataset, we can see an issue withincomplete or missing data:

Cameron Smith's "Date of Birth" field is Null, which indicatesmissing datathat needs to be filled in.

The format inconsistency in "Date of Birth" (e.g., "13-Jun" vs. "Dec 14") can also be problematic, requiring standardization.

Option A (Invalid data):Incorrect. The data is not necessarily invalid, but it is incomplete.

Option B (Redundant data):Incorrect. Redundant data means unnecessary duplication, which is not the case here.

Option C (Data outliers):Incorrect. Outliers refer to values that are extremely different from the rest of the dataset, which does not apply here.

Option D (Missing data):Correct.The "Date of Birth" field has missing values (e.g., "Null"), requiring data cleansing.

After writing the report, the most appropriate next step for the analyst is to complete a check for quality in the report. This involves reviewing the report for accuracy, clarity, completeness, consistency, and relevance. The analyst should ensure that the report addresses the director’s business questions and objectives, that the data and analysis are correct and reliable, that the tables and graphs are well-designed and easy to understand, that the descriptions and summary are concise and informative, and that there are no errors or inconsistencies in the report. A quality check will help the analyst to improve the presentation and communication of the report, as well as to avoid any misunderstandings or misinterpretations by the director1.

The correct answer is B. 154 mm.

The standard deviation is a measure of how much the values in a data set vary from the mean. To calculate the standard deviation, we need to follow these steps:

Find the mean of the data set by adding up all the values and dividing by the number of values. In this case, the mean is (300 + 430 + 170 + 470 + 600) / 5 = 394 mm.

Find the difference between each value and the mean, and square it. In this case, the differences and their squares are:

300 - 394 = -94, (-94)^2 = 8836

430 - 394 = 36, (36)^2 = 1296

170 - 394 = -224, (-224)^2 = 50176

470 - 394 = 76, (76)^2 = 5776

600 - 394 = 206, (206)^2 = 42436

Find the sum of the squared differences. In this case, the sum is 8836 + 1296 + 50176 + 5776 + 42436 = 108520.

Divide the sum by the number of values. In this case, the result is 108520 / 5 = 21704. This is called the variance.

Take the square root of the variance. In this case, the result is sqrt(21704) = 147.32 mm. This is called the standard deviation.

Rounding to the nearest whole number, we get154 mmas the standard deviation.

 The correct data type for text is string. A string is a data type that represents a sequence of characters, such as letters, numbers, symbols, or spaces. A string can be enclosed by single quotes (’ ') or double quotes (" ") in most programming languages. For example, ‘Hello’, “World”, and “123” are all strings. The other options are not data types for text, but for other kinds of values. A boolean is a data type that represents a logical value, either true or false. An integer is a data type that represents a whole number, such as 1, 0, or -5. A float is a data type that represents a number with a fractional part, such as 3.14, 0.5, or -2.7. Reference: Data Types - W3Schools