In a hall,
16 of the boys wore sweaters. After 20 boys who wore sweaters left the hall, the percentage of boys who wore sweaters decreased to 10%. How many boys in the hall did not wear sweaters?
| |
Wore sweaters |
Did not wear sweaters |
| Before |
1x9 =
9 u |
5x9 =
45 u |
| Change |
- 20 |
|
| After |
1x5 =
5 u |
9x5 =
45 u |
10% =
10100 =
110The number of boys who did not wear sweaters remains unchanged. LCM of 5 and 9 is 45.
Number of boys who wore sweaters and left
= 9 u - 5 u
= 4 u
4 u = 20
1 u = 20 ÷ 4 = 5
Number of boys who did not wear sweaters
= 45 u
= 45 x 5
= 225
Answer(s): 225
