The average fuel efficiency

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The average fuel efficiency

by BTGmoderatorDC » Mon Feb 12, 2018 8:26 pm
The average fuel efficiency of vehicles sold nationwide during the period 2000- 2004 was 25 miles per gallon; the corresponding figure during the period 1995- 1999 was 20 miles per gallon. The national average price of gasoline during the period 2000-2004 was $2 per gallon; the corresponding figure during the period 1995-1999 was $1.60 per gallon.

The statements above, if true, best support which of the following conclusions?

A)The average fuel efficiency of vehicles sold nationwide should reach 30 miles per gallon for the period 2005-2009.
B)The national average price of gasoline during 1997 was lower than the corresponding price during 2003.
C) Rising gasoline prices led consumers to purchase more fuel-efficient cars.
D)Between the two described time periods, the national average fuel efficiency and the national average gasoline price both increased at roughly the same rate.
E)Consumers spent more money on gasoline during the period 2000-2004 than during the period 1995-1999.

What's wrong with options B and C?

OA D
Source: — Critical Reasoning |

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by ErikaPrepScholar » Tue Feb 13, 2018 6:53 am
Let's rephrase what we know from the passage so we don't get confused:
- Avg. fuel efficiency was higher from 2000-2004 than it was from 1995-1999 (25 mpg vs. 20 mpg)
- Avg. gas price was higher from 2000-2004 than it was from 1995-1999 ($2/gal vs. $1.60/gal)

A)The average fuel efficiency of vehicles sold nationwide should reach 30 miles per gallon for the period 2005-2009.

This assumes that fuel efficiency will continue to increase by 5 mpg every five years. The passage doesn't indicate that this trend will continue, just that it occurred from 1995-2004. Eliminate.

B)The national average price of gasoline during 1997 was lower than the corresponding price during 2003.
The passage indicates that the average price across 1995, 1996, 1997, 1998, and 1999 is lower than the average price across 2000, 2001, 2002, 2003, and 2004. This doesn't mean that every year from 1995-1999 must be lower than every year from 2000-2004. Maybe 1997 was a surprisingly expensive year for gas, while 2003 was surprisingly inexpensive. All five years could still average out to lower for 1995-1999 and higher for 2000-2004. Eliminate.

C) Rising gasoline prices led consumers to purchase more fuel-efficient cars.

The passage doesn't indicate any sort of causation. Maybe fuel efficiency increased because the technology just wasn't there yet before 2000. Maybe car manufacturers stopped making as many fuel inefficient cars. We don't know *why* fuel efficiency increased - we just know that it did. Eliminate.

D)Between the two described time periods, the national average fuel efficiency and the national average gasoline price both increased at roughly the same rate.
An increase from 20 mpg to 25 mpg is a 25% increase. An increase from $1.60/gal to $2.00/gal is also a 25% increase. So fuel efficiency and gas price increased at roughly the same rate. This works!

E)Consumers spent more money on gasoline during the period 2000-2004 than during the period 1995-1999.

We know that gas cost more from 2000-2004. However, we don't know that consumers bought as much gas from 2000-2004. They may have purchased far less gas, so that even though it was more expensive, it cost less in total. This is supported by the fact that fuel efficiency was higher, meaning that consumers wouldn't have to buy as much gas to get where they need to go. Eliminate.

So the correct answer is D.
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