From the given box and whisker's plot, we have
[tex]Q_1=3\\
Q_2=5\\
Q_3=7\\
Max=10\\
Min=1[/tex]
Now, we know that there is half data distributed between the lower and upper quartiles.
Also, we have to find that how many schools have participated for 3 to 7 years. It means we need to find the number of years in between Q1 and Q3.
The total number of schools is 16.
Hence, number of schools have participated for 3 to 7 years is given by half of the total number of schools.
=[tex]\frac{1}{2} \times 16\\
\\
=8[/tex]
Therefore, 8 schools have participated for 3 to 7 years.
D is the correct option.
