1. Question 1

A/B testing — the correct answer

• A/B testing ✅

• Hypothesis testing ❌

• Time series analysis ❌

• Regression analysis ❌

Explanation:
Two groups receive different versions of a message to compare engagement — classic A/B testing.

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2. Question 2

Correct statements:

• Before conducting a test, data professionals choose the sample size. ✅

• Sampling is the process of selecting a subset of data from a population. ✅

• A population includes every possible element to be measured. ✅

• Inferential statistics is the process of selecting a subset of data from a population. ❌

Explanation:
Inferential statistics draws conclusions about a population from a sample. Sampling is the act of selecting the subset.

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3. Question 3

• Descriptive statistics ✅

• Statistical significance ❌

• Inferential statistics ❌

• Confidence intervals ❌

Explanation:
They summarize and understand a large dataset using a table, which is descriptive statistics.

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4. Question 4

• Parameter ✅

• Sample ❌

• Range ❌

• Measure ❌

Explanation:
A parameter is a numerical characteristic of a population.

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5. Question 5

• Mean ✅

• Range ❌

• Mode ❌

• Standard deviation ❌

Explanation:
Average time spent = mean.

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6. Question 6

• 2 ✅

• 4 ❌

• 10 ❌

• 7 ❌

Explanation:
Mode = most frequent value → 2 appears twice.

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7. Question 7

• Range ✅

• Percentile ❌

• Standard deviation ✅

• Variance ✅

Explanation:
Range, variance, and standard deviation measure spread (dispersion).

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8. Question 8

Values: 1, 2.4, 3.2, 5, 2.8
Range = 5 − 1 = 4

• 4 ✅

• 5 ❌

• 3.2 ❌

• 2.4 ❌

Explanation:
Range = max − min.

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9. Question 9

IQR = Q3 − Q1 = 70,000 − 40,000 = 30,000

• $30,000 ✅

• $40,000 ❌

• $15,000 ❌

• $55,000 ❌

Explanation:
IQR measures the middle 50% of data.

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10. Question 10

• Mode ✅

• Median ❌

• Mean ❌

• Standard deviation ❌

Explanation:
For categorical data, describe() returns count, unique, top (mode), and frequency.

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🧾 Summary Table