A sample of seventh and eighth grade students were asked how many minutes they spent online last night. The results were recorded in the box-and-whisker plots shown. What can you conclude?
A.
Eighth grade students have more variation in the amount of time spent online last night.
B.
Seventh grade students have more variation in the amount of time spent online last night.
C.
The sample size of seventh grade students is less than the sample size of eighth grade students.
D.
The sample sizes are equal.

The correct answer is A. Eighth grade students have more variation in the amount of time spent online last night.

Step-by-step explanation:

1st reason: Eighth grade students range is greater than the range of seventh grade students.

We can prove it this way:

Eighth grade students range ≅ 110 - 10

Eighth grade students range ≅ 100 minutes

Seventh grade students range ≅ 100 - 10

Eighth grade students range ≅ 90 minutes

100 > 90

2nd reason: Eighth grade students 2nd and 3rd quartiles are greater than the 2nd and 3rd quartiles of seventh grade students, that means that their results are more spread out than seventh grade students results.

We can prove it this way:

Eighth grade students 2nd and 3rd quartiles or 50% of all the eighth grade students spent between 40 and 100 minutes online last night.

Seventh grade students 2nd and 3rd quartiles or 50% of all the seventh grade students spent between 30 and 70 minutes online last night.

use this formula:

p(a\b) = p(a and b)/p(b).

take it from here.