Question 1043134
We have the average for 12 of the 20 students which is 7.5
The maximum total of scores is 12 * 7.5 + 8 * 10
 90 + 80 = 170
So the maximum possible average is 170/20 = 8.5
Now let's find the minimum possible average.
 90 + 8 * 0 = 90
90/20 = 4.5, which is the minimum possible average.
So one could write 4.5 <= x <= 8.50
Only answer D is consistent with this.