Question

the stem-and-leaf plots below show the scores of 15 ninth graders and 15 tenth graders in a competition.
competition scores for ninth graders
stem | leaf
5 | 2 3 4 4 4
4 | 2 4 6 8 9
3 | 3 5 5 5 5
competition scores for tenth graders
stem | leaf
5 | 4 6 7 8 8 9
4 | 1 2 2 2 7 8 9
3 | 8 9
key: 5|8 represents 58
how much greater is the mode of the tenth graders scores than the mode of the ninth graders scores?
options: 1, 4, 5, 7

Explanation:

Step1: Find 9th graders' mode

Stem 3: leaves 3,5,5,5,5 → scores 33,35,35,35,35. Mode=35.

Step2: Find 10th graders' mode

Stem 4: leaves 1,2,2,2,2,7,8,9 → scores 41,42,42,42,42,... Mode=42.

Step3: Calculate difference

$42 - 35 = 7$

Answer:

7