Average of math class after taking test 2, f(2) = 0.2 * (2) + 79 = 79.4
Average of science class after taking test 2, g(2) = 84, (as shown in the table)
Average of math class after taking test 4, f(4) = 0.2 * (4) +79 =79.8
Average of science class after taking test 4, g(4) = 80 (Explanation below)
so, f(4) < g(4)
Explanation:
the table follows a straight line, y- y1 = m (x-x1) ---------------------------(a)
y1=86
x1 = 1
m = (86-84)/(1-2) = -2
now putting the value of y1, x1 and m in eq. (a) we get:
y-86 = -2(x-1)
now since we have to compute for test 4, so x = 4
Therefore, y-86 = -2(4 -1)
=> y-86 = -6
=> y = 80