Practice Test GeeksAMC 8 - American Mathematics Competition 8 Practice Test
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Data Analysis & Statistics Flashcards

7 cards from real AMC 8 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 & Statistics flashcards as text

  1. A student scored 80, 85, 90, and 75 on four tests. What score is needed on the fifth test to achieve an average of 85?

    Answer: 95

    The sum of 5 scores must be 85×5=425; current sum is 330, so the fifth score must be 425−330=95.

  2. A stem-and-leaf plot shows: Stem 4: leaves 2,5,8; Stem 5: leaves 1,3,7; Stem 6: leaves 0,4. What is the median?

    Answer: 55

    The 8 values are 42,45,48,51,53,57,60,64; the median is the average of the 4th and 5th values: (53+57)/2=55.

  3. A class of 10 boys has an average score of 75, and a class of 15 girls has an average score of 80. What is the combined class average?

    Answer: 78

    Combined average = (10×75 + 15×80)/(10+15) = (750+1200)/25 = 1950/25 = 78.

  4. The data set {4, 7, 9, x, 12} has a mean of 8. What is the value of x?

    Answer: 8

    (4+7+9+x+12)/5 = 8 means 32+x = 40, so x = 8.

  5. Scores of 60, 70, 80, and 90 in a frequency table have frequencies of 2, 5, 8, and 5. What is the mode?

    Answer: 80

    The mode is 80 because it has the highest frequency of 8 occurrences.

  6. A store's daily sales: Mon=$200, Tue=$250, Wed=$180, Thu=$300, Fri=$270. On which day did sales increase the most from the previous day?

    Answer: Thursday

    Thursday's increase was $300−$180=$120, which is greater than Tuesday's $50 increase; Wednesday and Friday were decreases.

  7. In the data set {3, 5, 7, 9, 11}, the largest value changes from 11 to 21. Which measure of central tendency changes?

    Answer: Mean only

    The median is still the middle value 7, but the mean increases because the sum is larger; mode is unchanged.