In a basketball court,
310 of the girls wore sweaters. After 80 girls who wore sweaters entered the basketball court, the percentage of girls who wore sweaters increased to 70%. How many girls in the basketball court did not wear sweaters?
| |
Wore sweaters |
Did not wear sweaters |
| Before |
3x3 =
9 u |
7x3 =
21 u |
| Change |
+ 80 |
|
| After |
7x7 =
49 u |
3x7 =
21 u |
70% =
70100 =
710The number of girls who did not wear sweaters remains unchanged. LCM of 7 and 3 is 21.
Number of girls who wore sweaters and left
= 49 u - 9 u
= 40 u
40 u = 80
1 u = 80 ÷ 40 = 2
Number of girls who did not wear sweaters
= 21 u
= 21 x 2
= 42
Answer(s): 42
