In a school with 604 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average age of the school is 11 years 9 months, then the number of girls in the school is	Choose the correct option:
A) 150
B) 151
C) 250
D) 350
E) None
Sol.   Let the number of grils be x.   Then, number of boys = (600 - x).   Then, (11 3/4 × 604)   ⇔ 11x + 12(604 - x) ⇔ x = 7248 - 7097 ⇔ 151.   Answer 151
<result>B</result>
In a school with 604 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average age of the school is 11 years 9 months, then the number of girls in the school is