Most graphing calculators will do weighted averages pretty easily. It is mostly a matter of data entry.
mx = -2
my = 10
(x, y) = (mx, my)/10 = (-0.2, 1)
So, the ration is 17:3, you know that. Therefore, the change from # of students to the 17 is the same change as # teachers to 3. Knowing this, you also know that the total # of people ihas the same change as the total ratio. So 17+3 = 20. 740/20 = 37. So the change is 37. 3x37= 111 17x37=629
You can check to make sure this answer is correct by adding the two final numbers. 111+629 = 740. (Some find it easier to see lined up really pretty)
17 -- 3 total 20
x -- y total 740
Or, if you are visual, look at the picture I drew:
Answer:
The answer to 9 is table A
Step-by-step explanation:
The table has the value of x as -4 in two different spots, therefore it would fail the vertical line test. You could change one of the two values with -4 to anything but -4
