Final answer:
The least possible number of people in the choir is 6.
Step-by-step explanation:
To find the least possible number of people in the choir, we need to find the least common multiple (LCM) of 6. The LCM is the smallest number that is a multiple of both 6 and the missing number in the last row. Since the last row is one person short, the missing number is 1. Therefore, we need to find the LCM of 6 and 1.
The LCM of 6 and 1 is 6. So the least possible number of people in the choir is 6.