30% of the people are performers for a concert and the rest are spectators. 60% of the spectators are parents and there are 1260 less child spectators than parent spectators. How many parent spectators must join so that 71% of the people are parent spectators?
|
Performers |
Spectators |
|
3x5 |
7x5 |
|
|
Children |
Parents |
|
|
2x7 |
3x7 |
Before |
15 u |
14 u |
21 u |
Change |
|
|
+ ? |
After |
29x1 = 29 u |
71x1 = 71 u |
30% =
30100 =
310 60% =
60100 =
35 71% =
71100 =
71100The total number of spectators at first is repeated. Make the total number of spectators the same. LCM of 7 and 5 is 35.
Number of less child spectators than parent spectators at first
= 21 u - 14 u
= 7 u
7 u = 1260
1 u = 1260 ÷ 7 = 180
If some parent spectators join, the total number of child spectators and performers remains unchanged.
Number of parent spectators who must join so that 71% of the people are parent spectators
= 71 u - 21 u
= 50 u
= 50 x 180
= 9000
Answer(s): 9000