Given that the iq scores for large populations are centered at 100.
To get what percent of these 78 students have scores above 100 we conduct a normal distribution probability of the data.
P(x > 100) = P(z > (100 - 100)/sd) = P(z > 0) = 1 - P(z < 0) = 1 - 0.5 = 0.5 = 50%