Raffe wrote three math tests each worth 20% of his final grade. Raffe got marks of 68%, 74%, and 84 %. What mark must Raffe get on the final exam (worth 40%) if Raffe wants a final grade of 70%?
Let x be the mark Raffe must get on the final exam.
Raffe's final grade will be calculated as follows:
0.2(68) + 0.2(74) + 0.2(84) + 0.4(x) = 70
13.6 + 14.8 + 16.8 + 0.4x = 70
45.2 + 0.4x = 70
0.4x = 24.8
x = 62
Raffe must get at least 62% on the final exam to achieve a final grade of 70%.