SOLUTION: 1. Fifteen graduating students agreed to buy s laboratory apparatus costing C to be donated yo yheir school. All but 3 were able to give contributions. By how much was the contribu

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: 1. Fifteen graduating students agreed to buy s laboratory apparatus costing C to be donated yo yheir school. All but 3 were able to give contributions. By how much was the contribu      Log On


   

Question 936919: 1. Fifteen graduating students agreed to buy s laboratory apparatus costing C to be donated yo yheir school. All but 3 were able to give contributions. By how much was the contribution of each who contributed increased?
A. C/10
B. C/15
C. C/30
D. C/60
2. If 3/5 of the students are dismissed at 3:30 p.m. and 3/4 of the remainder at 4:00 p.m., what fraction of the students are dismissed at other times?
A. 3/20
B. 1/10
C. 1/5
D. 3/10
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
1.
if all give contributions each one will be giving %281%2F15%29 of C, or C%2F15
so, answer is: B. C%2F15
2.
there is x students
If "3%2F5 of the students are dismissed at 3%3A30p.m", we have %283%2F5%29x dismissed
x-%283%2F5%29x+ will be reminder
and if 3%2F4 of the remainder dismissed at 4%3A00p.m.,we have :
%283%2F4%29%28x-%283%2F5%29x%29
=%283%2F4%29%285x%2F5-3x%2F5%29
=%283%2F4%29%282x%2F5%29
=6x%2F20
=3x%2F10 are dismissed at 4:00 p.m
all together:
%283%2F5%29x%2B3x%2F10 are dismissed which is %286%2F10%29x%2B3x%2F10=9x%2F10
so,we can write x as x=10x%2F10, then we have 10x%2F10-9x%2F10=%281%2F10%29x=> means 1%2F10 of the students are dismissed at other times
and your answer is: B. 1%2F10