percentage rat killing..

[ska7945]

33. Forty percent of the rats included in an experiment were male rats. If some of the rats died during the experiment and 30% 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 rats?

1)9/14
2)3/4
3)9/11
4)6/7
5)7/8

provide your reasoning please.
answer: A

[sudhir3127]

My answer is A

let there be 100 rats..

40 are males 60 female.

Assume the total number of rats that died were X
thus 30% male rats dies = 0.3 X
female rats = 0.7X

thus the ratio is

(0.3X/40)/(0.7X/60) = 9/14.

Hope its clear

[Scott@TargetTestPrep]

33. Forty percent of the rats included in an experiment were male rats. If some of the rats died during the experiment and 30% 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 rats?

1)9/14
2)3/4
3)9/11
4)6/7
5)7/8

provide your reasoning please.
answer: A

Solution:

We can let the total number of rats in the experiment be 100. Thus 40 are male rats and 60 are female rats. We can also let the total number of rats that died be 50. Thus, 15 male rats died, and 35 female rats died. We see that the death rate of the male rats is 15/40 = 3/8 and that of the female rats is 35/60 = 7/12. Therefore, the ratio is (3/8)/(7/12) = 3/8 x 12/7 = 3/2 x 3/7 = 9/14.

Answer: A