SOLUTION: 1)Two high school classes took the same test. One class of 20 students made an average grade of 80%; the other class of 30 students made an average grade of 70%. What is the aver

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Question 36545: 1)Two high school classes took the same test. One class of 20 students made an average grade of 80%; the other class of 30 students made an average grade of 70%. What is the average grade for all students in both classes?
2)The marching band of Success University is practicing for a drill. Two hundred members equally spaced form a large circle and each member is numbered consecutively. What is the number of the member who stands directly across from number 9?
3)Mary’s age is twice Tom’s age and one-third of Sally’s age. If the sum of their ages is 99, how old is Mary?
4)If a 5x9x12 rectangular block of wood is painted red and then cut into 540 1x1x1 cubes, how many cubes will have red paint on them?

Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
(.8*20+.7*30)/50=(16+21)/50 or 37/50=.74 grade for all 50 students.
100+9=109 the number opposite #9 100 is opposite 0 then add 9 to each we get 9 & 109
m+m/2+3m=99 or 4m+m/2=99 or (8m+m)/2=99 or 9m/2=99 or 9m=99*2 or 9m=198 or m=22
thus Mary is 22 Toms 1/2*22=11 & Sally is 3*22=66 thus 22+11+66=99 or 99=99
a 9*12*5 cube has 2 faces 9*12=216 now we have 2 faces 3*9=54 & 2 faces 3*12=72
adding up all these exclusive faces we get 216+54+72=342