a. The two data do not have the same center
For the sixth-grade students,
[tex]\text{Mode }\approx\text{ 90}[/tex]For the seventh-grade students,
[tex]\text{Mode }\approx\text{ 10}2[/tex]Hence, the seventh grade is higher than the sixth grade.
b. The greater spread:
For the sixth grade:
[tex]\text{Spread = 5}[/tex]For the seventh grade:
[tex]\text{Spread = }7[/tex]Hence, the spread for the seventh grade is higher
c. Overall, the students for the seventh grade sent more text messages