Question

A survey was given to 140 students. On average, 2 out of 7 students floss every day. How many students do NOT floss every day?

Answer 1

If on average 2 out of 7 students use floss every day, then among 140 students use floss every day

$140 \cdot \frac{2}{7} = 40$ students.

Then don't floss every day 140-40=100 students.

Answer: 100 students.