【Analysis and Solution】
There are $90 \div 1.5=60$ students in the third grade.
【Question 10】
The school is to distribute 90 storybooks to third-grade students. If distributed at a rate of 1 book per student, there will be leftovers; if the remaining books are then distributed at a rate of 1 book for every two students, they will be exactly distributed. Therefore, the number of third-grade students is $\qquad$ people.