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