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Tough and Tricky questions: Mixture Problems.

Sixty percent of the rats included in an experiment were female rats. If some of the rats died during an experiment and 70 percent 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?

A) 7 : 2

B) 7 : 3

C) 2 : 7

D) 3 : 7

E) Cannot be determined from the information given

Kudos for a correct solution.Source: Chili Hot GMAT

Let there be \(100\) rats in total.

No. of female rats = \(60\)

No. of male rats = \(40\)

No. of rats that died = \(x\).

No. of dead male rats = \(0.7x\)

No. of dead female rats = \(0.3x\)

Death rate of male rats = No. of dead male rats/Total male rats.

Death rate of male rats = \(\frac{0.7x}{40}\)

Death rate of female rats = \(\frac{0.3x}{60}\)

Ratio = \(\frac{0.7x*60}{0.3x*40} = \frac{0.7*3}{0.3*2} = \frac{7*3}{3*2} = \frac{7}{2}\). Ans - A.

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