Twelve boys and N girls sat for a test the mean of the boys scores and that of the girls were 5 and 8 respectively, find N if the total score was 180
Since we know that there were 12 boys, and their mean score was 5, we can say that they scored a total of 60 points.
We can also say that the girls scored a total of 8N points. We can form this equation:
60 + 8N = 180
8N = 120
N = 15
Therefore, there were 15 girls.