#9 - Global surveys estimate the earth’s population of

[deck1134]

Hello PowerScore,

I am somewhat confused by answer D. Though I chose answer A, isn't it also true that if both the Male and Females fell by 2/3 in 15 years, then the species is in danger of extension? Is that not the same as answer choice A?

Thanks.

[Adam Tyson]

I think you might mean answer C, deck? The one about the numbers of male and female turtles? The reason that isn't a necessary assumption of this argument is that the argument is about percentages, not numbers, so an answer that is only about numbers cannot be correct.

Imagine this: The population of turtles years ago was 100 turtles. Of those, 75 were nesting females and 25 were all the others - 15 males of all sorts and 10 females that aren't nesting. Now, the nesting females dropped by two thirds, so that today there are only 25 of them. Did the author have to assume that the numbers of males and females are the same in order to conclude that the species is in danger of extinction? Not at all! In fact, in this particular case having an equal number of males and females would mean we had a GAIN of at least 10 males, maybe more if there are also some non-nesting females still around. That answer would actually hurt the conclusion, because the total population didn't suffer nearly as much of a loss as two-thirds.

Beware of answers about numbers when the question is about percentages, and vice versa!