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Question 251978: The ratio of females to males in class is 7 to 4. If 3 females and 12 males are absent tomorrow, the ratio of females to males becomes 5 to 2. If this occurs, how many students will be in class tomorrow ?
Found 2 solutions by ptaylor, palanisamy:
Answer by ptaylor(2198)   (Show Source):
You can put this solution on YOUR website! Let x=initial number of students
Number of females=(7/11)x
Number of males=(4/11)x
If 3 females are absent tomorrow, we will have (7/11)x-3 females remaining
If 12 males are absent tomorrow, we will have (4/11)x-12 males remaining
so, (7/11)x-3=(5/7)(x-15) and/or (BOTH SHOULD GIVE THE SAME ANSWER)
(4/11)x-12=(2/7)(x-15)
Multiply the first equation by 77
49x-231=55x-825 subtract 55x from and add 231 to each side
49x-55x=-825+231
-6x=-594
x=99---number of students in the initial class
x-15=99-15=84 #students in class tomorrow--------------------ANSWER
Hope this helps---ptaylor
Answer by palanisamy(496)  (Show Source):
You can put this solution on YOUR website! Let the number of females be 7x
Then,the number of males is 4x
3 females and 12 males will be absent tomorrow,
So,tomorrow the number of females will be 7x-3 and the number of males is 4x-12
Given, (7x-3)/(4x-12) = 5/2
2(7x-3) = 5(4x-12)
14x-6 = 20x-60
54 = 6x
x = 9
Total number of students tomorrow = 7x-3+4x-12
= 11x-15
= 11x9-15
=84
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