Answer:
61
Explanation:
The mean of the 400 students can be calculated as the sum of the number of students by the mean score divided by the 400 students, so
[tex]\begin{gathered} \text{ mean = }\frac{(66\times150)+(58\times250)}{400} \\ \\ \text{ mean = }\frac{9900+14500}{400} \\ \\ \text{ mean = }\frac{24400}{400} \\ \\ \text{ mean = 61} \end{gathered}[/tex]Therefore, the mean score of the 400 students is 61
