Question

Which equation best represents the data in the table if the math grade y depends on the number of days absent x?

Days Absent 0 2 4 6 8
Grade % 90 85 80 75 70
A. y=2/5x+90
B. y=-2/5x+90
C. y=5/2x+90
D. y=-5/2x+90

Answer 1

The equation y= -5/2x+90 best represents the data in the table. Option D is the correct answer.

Explanation:

To find the correct equation out of the four options, substitute y= grade% and x= days absent.

Check for option A)

when x= 0, y= 2/5(0)+90 = 90. option A satisfies.

when x= 2, y= 2/5(2)+90 = (4/5)+90 ≠ 85. option A does not satisfy.

Check for option B)

when x= 0, y= -2/5(0)+90 = 90. option B satisfies.

when x= 2, y= -2/5(2)+90 = (-4/5)+90 ≠ 85. option B does not satisfy.

Check for option C)

when x= 0, y= 5/2(0)+90 = 90. option C satisfies.

when x= 2, y= 5/2(2)+90 = (5)+90 = 95 ≠ 85. option C does not satisfy.

Check for option D)

when x= 0, y= -5/2(0)+90 = 90. option D satisfies.

when x= 2, y= -5/2(2)+90 = (-5)+90 = 85. option D satisfies.

when x= 4, y= -5/2(4)+90 = (-5*2)+90 = -10+90 = 80. option D satisfies.

when x= 6, y= -5/2(6)+90 = (-5*3)+90 = -15+90 = 75. option D satisfies.

when x= 8, y= -5/2(8)+90 = (-5*4)+90 = -20+90 = 70. option D satisfies