In an audition of 30 singers, the average score was 66 points. Given that the average score of the boy singers was 80 points and that of the girl singers was 50 points, find the number of girl singers who participated in the audition.
| |
Boy singers |
Girl singers |
Total |
| Number |
1 u |
30 - 1 u |
30 |
| Value |
80 |
50 |
|
| Total value |
80 u |
1500 - 50 u |
1980 |
Number of boy singers = 1 u
Number of girl singers = 30 - 1 u
Total score of the boy singers
= 1 u x 80
= 80 u
Total score of the girl singers
= 50 x (30 - 1 u)
= 1500 - 50 u
Total score of the singers
= 80 u + 1500 - 50 u
= 80 u - 50 u + 1500
= 30 u + 1500
Total score of the singers
= 30 x 66
= 1980
30 u + 1500 = 1980
30 u = 1980 - 1500
30 u = 480
1 u = 480 ÷ 30 = 16
Number of girl singers
= 30 - 1 u
= 30 - 16
= 14
Answer(s): 14
