AMC 8 Data Analysis & Statistics 2

Question 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?

Accepted Answer

95

Answer

90

Answer

92

Answer

88

Question 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?

Accepted Answer

55

Answer

53

Answer

57

Answer

51

Question 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?

Accepted Answer

78

Answer

77

Answer

77.5

Answer

78.5

Question 4

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

Accepted Answer

8

Answer

6

Answer

7

Answer

9

Question 5

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

Accepted Answer

80

Answer

70

Answer

75

Answer

90

Question 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?

Accepted Answer

Thursday

Answer

Tuesday

Answer

Wednesday

Answer

Friday

Question 7

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

Accepted Answer

Mean only

Answer

Median only

Answer

Both mean and median

Answer

Mode only