Answer:
512
Step-by-step explanation:
Let the number of 7th graders in the school is x.
As three-quarters of them play at least one sport, so, the number of 7th graders who play sport = [tex]\frac 3 4 x[/tex].
Among the 7th graders who play sports, half of them play more than one sport. So, the number of 7th graders who play more than one sport [tex]= \frac 1 2\times \frac 3 4 x=\frac 3 8 x[/tex].
Among the 7th graders who play more than one sport, one-third of them play more than two sports. So, the number of 7th graders who play more than two sport [tex]= \frac 1 3\times \frac 3 8 x=\frac 1 8 x[/tex].
Among the 7th graders who play more than two sports, one-quarter of them play more than three sports.
So, the number of 7th graders who play more than three sport [tex]= \frac 1 4\times \frac 1 8 x=\frac{1}{32} x[/tex].
7th graders play more than three sports at the school= 16
[tex]\Rightarrow \frac{1}{32} x=16[/tex]
[tex]\Rightarrow x =16 \times 32[/tex]
[tex]\Rightarrow x = 512[/tex]
Hence, the total numbers of 7th graders in the school are 512.