Practice Test GeeksGRE Practice Test
← All GRE Flashcard Decks

Probability and Statistics Concepts Flashcards

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

Read the first 7 Probability and Statistics Concepts flashcards as text

  1. A box has cards numbered 1 to 20. What is the probability of drawing a multiple of 5?

    Answer: 1/5

    The multiples of 5 are 5, 10, 15, 20 — four out of twenty, giving 4/20 = 1/5.

  2. Given P(A and B) = 0.2 and P(B) = 0.5, what is the conditional probability P(A | B)?

    Answer: 0.4

    P(A | B) = P(A and B)/P(B) = 0.2/0.5 = 0.4.

  3. The variance of a data set is 16. What is its standard deviation?

    Answer: 4

    Standard deviation is the square root of variance, √16 = 4.

  4. In a class of 30 students, 18 play soccer. What percent do not play soccer?

    Answer: 40%

    12 of 30 do not play soccer, which is 12/30 = 40%.

  5. Two independent events each have probability 0.5. What is the probability that neither occurs?

    Answer: 0.25

    P(neither) = (1−0.5)(1−0.5) = 0.5 × 0.5 = 0.25.

  6. Which of the following data sets has the largest standard deviation?

    Answer: {1, 5, 5, 9}

    The set {1, 5, 5, 9} has values spread farthest from the mean, giving the greatest dispersion.

  7. A survey reports a mean income that is much higher than the median income. This most likely indicates the distribution is:

    Answer: Right-skewed

    When the mean exceeds the median, high-value outliers pull the mean up, indicating right (positive) skew.