A cross country coach just announced that, by the end of the quarter, all students should run the 10 miles in less than 70 minutes. There are 15 students in the group.
6 of them ran 10 miles in 1 hour + 5 minutes,
4 of them ran 10 miles in 1 hour + 3 minutes,
2 of them ran 10 miles in 1 hour + 9 minutes,
3 of them ran 10 miles in 1 hour and 10 minutes.
How many students made the goal?

Express 70 minutes in the form of hours + minutes since most of the figures given were in that form, hence:
70 minutes = 60 minutes + 10 minutes = 1 hour + 10 minutes.
This means that for students to pass, they must run the 10-mile distance in less than this time set by the coach. Checking the students’ time one by one, only 3 out of 15 students were not able to run the 10 miles in less than 1 hour + 10 minutes.
15 - 3 = 12 students made the goal.