30% of the people are performers for a concert and the rest are spectators. 80% of the spectators are children and there are 630 more child spectators than parent spectators. How many child spectators must leave so that 12% of the people are child spectators?
|
Performers |
Spectators |
|
3x5 |
7x5 |
|
|
Parents |
Children |
|
|
1x7 |
4x7 |
Before |
15 u |
7 u |
28 u |
Change |
|
|
- ? |
After |
22x1 = 22 u |
3x1 = 3 u |
30% =
30100 =
310 80% =
80100 =
45 12% =
12100 =
325The 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 more child spectators than parent spectators at first
= 28 u - 7 u
= 21 u
21 u = 630
1 u = 630 ÷ 21 = 30
If some child spectators leave, the total number of parent spectators and performers remains unchanged.
Number of child spectators who must leave so that 12% of the people are child spectators
= 28 u - 3 u
= 25 u
= 25 x 30
= 750
Answer(s): 750