25% of the people are performers for a concert and the rest are spectators. 60% of the spectators are parents and there are 120 less child spectators than parent spectators. How many parent spectators must join so that 78% of the people are parent spectators?
|
Performers |
Spectators |
|
1x5 |
3x5 |
|
|
Children |
Parents |
|
|
2x3 |
3x3 |
Before |
5 u |
6 u |
9 u |
Change |
|
|
+ ? |
After |
11x1 = 11 u |
39x1 = 39 u |
25% =
25100 =
14 60% =
60100 =
35 78% =
78100 =
3950The 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 = 120
1 u = 120 ÷ 3 = 40
If some parent spectators join, the total number of child spectators and performers remains unchanged.
Number of parent spectators who must join so that 78% of the people are parent spectators
= 39 u - 9 u
= 30 u
= 30 x 40
= 1200
Answer(s): 1200