SOLUTION: The average mark on a test for a class of 35 students was 61%. The average mark obtained by the 15 girls in the class was 65%. What was the average mark obtained by the boys?

Algebra ->  Average -> SOLUTION: The average mark on a test for a class of 35 students was 61%. The average mark obtained by the 15 girls in the class was 65%. What was the average mark obtained by the boys?      Log On


   

Question 1052885: The average mark on a test for a class of 35 students was 61%. The average mark obtained by the 15 girls in the class was 65%. What was the average mark obtained by the boys?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
[ ave mark ] = [ total of marks ] / [ number of students ]
----------------------
For all the students:
++61+=+T+%2F+35+
+T+=+2135+
Total of marks for all students
------------------------------
For the girls:
+65+=+T%2F15+
+T+=+975+
Total of marks for girls
------------------------
+2135+-+975+=+1160+
and
+35+-+15+=+20+
---------------------
Let +x+ = the average mark for the boys
+x+=+1160%2F20+
+x+=+58+
The average mark for the boys is 58