PSLE The students of a test are divided equally into two groups. In the first group, there are 31 less boys than girls. In the second group, there are 13 more boys than girls. 40% of all the students are boys. How many students are boys?
|
First group |
Second group |
Total |
Comparison 1 |
50% |
50% |
100% |
Comparison 2 |
Girls (more) |
Boys (less)
|
Girls (less)
|
Boys (more) |
|
|
1 u + 31 |
1 u |
1 u + 9 |
1 u + 9 + 13 |
|
Comparison 3 |
Total boys |
Total girls |
|
|
40% |
60% |
100% |
Number of students in the first group and the second group is equal.
Percentage of students who are girls
= 100% - 40%
= 60%
Percentage of more girls than boys
= 60% - 40%
= 20%
Total number of girls
= 1 u + 31 + 1 u + 9
= 2 u + 40
Total number of boys
= 1 u + 1 u + 9 + 13
= 2 u + 22
Number of girls more than boys
= 40 - 22
= 18
20% of the students = 18
1% of the students = 18 ÷ 20 = 0.9
40% of the students
= 40 x 0.9
= 36
Number of students that are boys = 36
Answer(s): 36