Question

The teacher kept track of how long it took students to finish a test. After 20 minutes, 3 students had finished the test.

Answer 1

9 students finished the test 

Answer 2

Answer: D. 10 students finished the test.
How I got that:
20 x 4. Which got me 80. (You had to get after 70)
9.5 students finished but round that up to 10.