In a parade square,
18 of the pupils wore sweaters. After 220 pupils who wore sweaters entered the parade square, the percentage of pupils who wore sweaters increased to 75%. How many pupils in the parade square did not wear sweaters?
|
Wore sweaters |
Did not wear sweaters |
Before |
1x1 = 1 u |
7x1 = 7 u |
Change |
+ 220 |
|
After |
3x7 = 21 u |
1x7 = 7 u |
75% =
75100 =
34The number of pupils who did not wear sweaters remains unchanged. LCM of 7 and 1 is 7.
Number of pupils who wore sweaters and left
= 21 u - 1 u
= 20 u
20 u = 220
1 u = 220 ÷ 20 = 11
Number of pupils who did not wear sweaters
= 7 u
= 7 x 11
= 77
Answer(s): 77