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Data Analysis Flashcards

7 cards from real DSAT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Data Analysis flashcards as text

  1. A survey oversamples wealthy households because they are easier to contact by phone. Which type of error does this introduce?

    Answer: Sampling bias

    Systematically overrepresenting a subgroup creates sampling bias, making results unrepresentative of the full population.

  2. A dataset of 7 scores is: 55, 70, 72, 74, 76, 78, 99. What is the IQR?

    Answer: 8

    Q1 = 70, Q3 = 78, so IQR = 78 − 70 = 8.

  3. A researcher increases sample size from 100 to 400. How does the margin of error change, assuming the same confidence level?

    Answer: It is cut in half

    Margin of error is proportional to 1/√n; quadrupling sample size halves the margin of error.

  4. The line of best fit for advertising spend (x, in $1,000s) vs. sales (y, in $1,000s) is y = 3x + 10. Predict sales when advertising spend is $5,000.

    Answer: $25,000

    x = 5 (in $1,000s): y = 3(5) + 10 = 25, so predicted sales = $25,000.

  5. A dot plot shows 15 data points clustered between 20 and 30, with one point at 85. Which statement is true?

    Answer: The mean is higher than the median

    The outlier at 85 pulls the mean upward, making the mean greater than the median.

  6. A fair coin is flipped 3 times. What is the probability of getting exactly 2 heads?

    Answer: 3/8

    There are C(3,2) = 3 outcomes with exactly 2 heads out of 8 equally likely outcomes, giving 3/8.

  7. A class of 30 students took a test. The median score falls in the 70s. Which statement must be true?

    Answer: The 15th and 16th values when sorted are both in the 70–79 range

    For 30 data points, the median is the average of the 15th and 16th sorted values; both must be in the 70s for the median to fall there.