To find the minimum score, you will consider that the mean of 80 must spread out between all possible scores.
Because the last exam counts double, you will consider 5 scores.
5 x 80 = 400 total points are what Tina needs.
400 - (94 + 68 + 88) = 150.
She must earn half of 150 points on her exam to earn an 80% overall grade.
A 75 is what Tina will need.
