8 hours because 11/3 of an hour is 3 hours and 40 minutes. 12/9 is 4 hours. 1/3 is 20 minutes and if you add it all together you get 8 hours
Answer:
310
Step-by-step explanation:
total no.of students=1872
ratio of boys to girls=7:5
sum of ratio=total of students
12/12=1872
7/12=?
7/12*1872/1=1092which is the number of girls
1872-1092=780which is the number of boys
difference =1092-780= 310