|
|
| (3 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| − | ==Problem==
| + | #REDIRECT [[2007 AMC 10B Problems/Problem 14]] |
| − | | |
| − | Some boys and girls are having a car wash to raise money for a class trip to China. Initially <math>40</math>% of the group are girls. Shortly thereafter two girls leave and two boys arrive, and then <math>30</math>% of the group are girls. How many girls were initially in the group?
| |
| − | | |
| − | <math>\mathrm {(A)} 4</math> <math>\mathrm {(B)} 6</math> <math>\mathrm {(C)} 8</math> <math>\mathrm {(D)} 10</math> <math>\mathrm {(E)} 12</math>
| |
| − | | |
| − | ==Solution==
| |
| − | | |
| − | First, determine the total number of people in the group.
| |
| − | | |
| − | <math>2=10/100t</math>
| |
| − | | |
| − | <math>t=200/10=20</math>
| |
| − | | |
| − | Now find the original number of girls:
| |
| − | | |
| − | <math>40/100t = 800/100 = 8</math>
| |
| − | | |
| − | So, there are 8 girls, <math>\Rightarrow \fbox{C}</math>
| |
