There are 720 students in a school. The ratio of boys and girls in this school is 3:5. Find the total of girls & boys are there in this school?	Pick.
A) 320	B) 345	C) 450	D) 380	E) 400

Rationale: "in order to obtain a ratio of boys to girls equal to 3 : 5 , the number of boys has to be written as 3 x and the number of girls as 5 x where x is a common factor to the number of girls and the number of boys . the total number of boys and girls is 720 . hence 3 x + 5 x = 720 solve for x 8 x = 720 x = 90 number of boys 3 x = 3 × 90 = 270 number of girls 5 x = 5 × 90 = 450 c"
Answer: C