In a parade square,
15 of the boys wore ties. After 180 boys who wore ties entered the parade square, the percentage of boys who wore ties increased to 80%. How many boys in the parade square did not wear ties?
| |
Wore ties |
Did not wear ties |
| Before |
1x1 =
1 u |
4x1 =
4 u |
| Change |
+ 180 |
|
| After |
4x4 =
16 u |
1x4 =
4 u |
80% =
80100 =
45The number of boys who did not wear ties remains unchanged. LCM of 4 and 1 is 4.
Number of boys who wore ties and left
= 16 u - 1 u
= 15 u
15 u = 180
1 u = 180 ÷ 15 = 12
Number of boys who did not wear ties
= 4 u
= 4 x 12
= 48
Answer(s): 48
