Final answer:
The number of ways a teacher can select a group of 3 students to sit in the front row out of a class of 12 students is 220.
Step-by-step explanation:
In combinatorics, the number of ways to select a group of k objects from a set of n objects is given by the combination formula:
C(n, k) = n! / (k!(n-k)!)
For this question, we want to find the number of ways a teacher can select a group of 3 students to sit in the front row out of a class of 12 students. So, we have n = 12 and k = 3:
C(12, 3) = 12! / (3!(12-3)!) = 12! / (3!9!) = (12 * 11 * 10) / (3 * 2 * 1) = 220 ways
Therefore, there are 220 ways for the teacher to select a group of 3 students to sit in the front row.