Answer: They will next be together in the lab in 12 school days.
Step-by-step explanation:
To find the least common multiple of the numbers 3, 4, 6, and 7, you can list the multiples of each number until you find a multiple that the other numbers also share:
Multiples of 3: 3, 6, 9, 12, 15, 18, ...
Multiples of 4: 4, 8, 12, 16, 20, 24, ...
Multiples of 6: 6, 12, 18, 24, 30, 36, ...
Multiples of 7: 7, 14, 21, 28, 35, 42, ...
The least common multiple of 3, 4, 6, and 7 is 12, because it is the smallest multiple that all of the numbers share. Therefore, they will next be together in the lab in 12 school days.