Σx/n = mean
for 19 students Σx = 19 * 14 = 266
(266 + x)/20 = 15
Solve for x.
The teacher collected the test papers of 20 students and found that their average mark was 15. Before she wrote the marks in her mark book, she lost 1 paper. Find the mark for the missing paper, she worked out the average mark for the 19 students was 14. What was the mark on the missing paper?
2 answers
-231