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Rats

by sumanr84 » Thu Feb 04, 2010 9:30 am
Q : Sixty percent of the rats included in an experiment were female rats. If some of the rats died during an experiment and 70% of the rats that died were male rats, what was the ratio of the death rate among the male rats to the death rate among the female rates ?
A. 7:2
B. 7:3
C. 2:7
D. 3:7
E. Cannot be determined from the information given

Ans will follow later..
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by ajith » Thu Feb 04, 2010 9:45 am
sumanr84 wrote:Q : Sixty percent of the rats included in an experiment were female rats. If some of the rats died during an experiment and 70% of the rats that died were male rats, what was the ratio of the death rate among the male rats to the death rate among the female rates ?
A. 7:2
B. 7:3
C. 2:7
D. 3:7
E. Cannot be determined from the information given

Ans will follow later..
Say initially there were m male rates and f female rats

f/(f+m) = 6/10

f/m = 6/4

say k rats died
0.7k is male and .3k is female

death rate among males = .7k/m
death rate among females = 0.3k/f

Ratio =7/3*f/m
=7/3*6/4
=7/2

hence A
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by harsh.champ » Thu Feb 04, 2010 1:14 pm
sumanr84 wrote:Q : Sixty percent of the rats included in an experiment were female rats. If some of the rats died during an experiment and 70% of the rats that died were male rats, what was the ratio of the death rate among the male rats to the death rate among the female rates ?
A. 7:2
B. 7:3
C. 2:7
D. 3:7
E. Cannot be determined from the information given

Ans will follow later..
_______________

Suppose,initially x rats were there.
Hence,0.6x = female rats
0.4x= male rats

Suppose y rats died
Hence,0.7y=male dead rats
0.3y=female dead rats

Death rate among male rats = 0.7y/0.4x
Death rate among female rats = 0.3y/0.6x

Hence ,the answer would be (7/4)/(3/6)=7:2
So,A would be the correct answer choice.
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by sumanr84 » Thu Feb 04, 2010 6:43 pm
OA : A
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