Draw a circle around the ratio that is NOT EQUIVALENT to 6 to 10

1. 9 : 15

2. 3 : 15

3. 18 : 30

4. 5 : 3

i have been struggling all day, please help a sad girl out:)

The line plot below represents the number of letters written to overseas pen pals by the students at the waverly middle school.each x represents 10 students. how many students wrote more than 6 and fewer than 20 letters. a.250 b.240 c.230 d.220