The ratio is 4:3:1
let the ratio be 4x:3x:x
according to the question,4x+3x+x=40
8x=40
x=5
therefore amount of gravel=x*4=5*4=20

amount of sand=5*3=15

amount of cement=5*1=5
The answer is 1.804 hope it helps
The number of students in 5th grade is 60, since 24% of 250 is 60.
Since 90 is 38% if 250, 38 is going to be the percent of all students in sixth grade.
20% of 250 is 50, so the percent of all students in seventh grade is 50.
Finally, 45 is 18% of 250, so 18 percent of all students are in eight grade.
Hope this helped :)