40% of the people are performers for a concert and the rest are spectators. 60% of the spectators are parents and there are 480 less child spectators than parent spectators. How many parent spectators must join so that 60% of the people are parent spectators?
|
Performers |
Spectators |
|
2x5 |
3x5 |
|
|
Children |
Parents |
|
|
2x3 |
3x3 |
Before |
10 u |
6 u |
9 u |
Change |
|
|
+ ? |
After |
2x8 = 16 u |
3x8 = 24 u |
40% =
40100 =
25 60% =
60100 =
35 60% =
60100 =
35The total number of spectators at first is repeated. Make the total number of spectators the same. LCM of 3 and 5 is 15.
Number of less child spectators than parent spectators at first
= 9 u - 6 u
= 3 u
3 u = 480
1 u = 480 ÷ 3 = 160
If some parent spectators join, the total number of child spectators and performers remains unchanged.
Number of parent spectators who must join so that 60% of the people are parent spectators
= 24 u - 9 u
= 15 u
= 15 x 160
= 2400
Answer(s): 2400