How many girls are in the school if 40% of a school population is made up of 240 boys?
100% - 40% = 60% of the school's population are girls.
Since 40% is equal to 240 students, then 1% is equal to 240/40 = <<240/40=6>>6 students.
Hence, there are 60 x 6 = <<60*6=360>>360 girls.
#### 360