hemanthp wrote:
Deb: It ’ s worrisome that 80% of the people in this country know at least one person who did not finish high school.
Erik: But the average person has about one hundred different acquaintances, so, even if the normal high school dropout rate is only 10%, most people will probably know at least one dropout.
Erik ’ s argument relies on the assumption that:
- The normal dropout rate has remained very stable over time.
- The dropout rate varies little from region to region across the country.
- The number of people who know a dropout is usually over 80% of the population.
- The statistics cited by Deb don ’ t overstate the fraction of the population that actually does know a high school dropout.
- Being personally acquainted with a dropout causes more anxiety about the dropout problem than do the dropout statistics themselves.
Please discuss. I have already given the OA.
Let's try this:
Quote:
Zhou: The newspaper claims that 80% of the world's population knows someone from the United States of America, but I don't believe it for a second.
Valerie: Actually, that number seems quite reasonable. After all, Americans make up 5% of the population of the world. Since the average person has 100 acquaintances, it's no surprise if a few are American.
Valerie's argument sounds pretty fishy, huh? In fact, it
would be amazing if 80% of the world's population knew someone from the US. After all, the overwhelming majority of American live in one place--America! Valerie's logic would only apply if Americans were distributed more or less evenly among the globe, which they clearly are not. Many people in China, India, Africa, and South America would never have had the opportunity to meet anyone from the US.
The same assumption exists in Deb and Erik's discussion; the reason it's harder to spot is because in the case of graduation rates, the its not obvious incorrect. One could perfectly reasonably assume that students drop out at relatively consistent rates across a small country. But what if they didn't? If ALL the country's dropouts were normally confined to one or two provinces, but now 80% of the entire country's population knows a dropout, Erik would be mistaken. Deb's statistic would be cause for alarm, as it would indicate the problem was spreading! On the other hand, if the 10% dropout rate was universal across the country, then Erik is right: Deb's statistic is unsurprising and not alarming. Thus, (B) clearly identifies the assumption in Erik's argument.
Hope this helps!