For a television program about astrology, investigators went into the street and found twenty volunteers born under the sign of Gemini who were willing to be interviewed on the program and to take a personality test. The test confirmed the investigators¡¯ personal impressions that each of the volunteers was more sociable and extroverted than people are on average. This modest investigation thus supports the claim that one¡¯s astrological birth sign influence one¡¯s personality.

Which one of the following, if true, indicates the most serious flaw in the method used by the investigators?

(A) The personality test was not administrated or scored personally by the investigators.

(B) People born under astrological signs other than Gemini have been judged by astrologers to be much less sociable than those born under Gemini.

(C) The personal impressions the investigators first formed of other people have tended to be confirmed by the investigators¡¯ later experience of those people.

(D) There is not likely to be a greater proportion of people born under the sign of Gemini on the street than in the population as a whole.

(E) People who are not sociable and extroverted are not likely to agree to participate in such an investigation.

Photovoltaic power plants produce electricity from sunlight. As a result of astonishing recent technological advances, the cost of producing electric power at photovoltaic power plants, allowing for both construction and operating costs, is one-tenth of what it was 20 years ago, whereas the corresponding cost for traditional plants, which burn fossil fuels, has increased. Thus, photovoltaic power plants offer a less expensive approach to meeting demand for electricity than do traditional power plants.

The conclusion of the argument is properly drawn if which one of the following is assumed?

(A) The cost of producing electric power at traditional plants has increased over the past 20 years.

(B) Twenty years ago, traditional power plants were producing 10 times more electric power than were photovoltaic plants.

(C) None of the recent technological advances in producing electric power at photovoltaic plants can be applied to producing power at traditional plants.

(D) Twenty years ago, the cost of producing electric power at photovoltaic plants was less than 20 times the cost of producing power at traditional plants.

(E) The cost of producing electric power at photovoltaic plants is expected to decrease further, while the cost of producing power at traditional plants is not expected to decrease.

Please separate topics in the future to ease discussion
My answers are 1-E and 2-C
1-
A) we are not interested in this
B) this actually strengthens the conclusion
C) what happens in the future is out of scope and does not pertain to the potential flaw in the current research
D) we are not interested in the sample's representativeness
E) if this is true, then how can the investigators say that other signs are less sociable than Geminis? His research would be then be biased by not including any of the other less sociable/extroverted persons

2-
A) this is explicitly mentioned in the text
B) we are not interested by the amount of electricity produced. We want to know it's viability in terms of cost
C) let's negate this. Then if technology can be transfered from photovoltaic plants to traditional ones, how can the cost of traditional plants have increased while that of photovoltaic ones decreased? C needs to hold true
D) this is a tricky one and I almost fell for it. Let's say that cost of traditional plants 20yrs ago = 1$ and cost of photovoltaic plants was 20$. Then cost of photovoltaic plant today = 20$ * 1/10 = 2$. If cost of traditional plant today is 1.50$, then this needs not be true
E) what happens in the future we are not interested in
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Best Regards,

Paul

It was me who posted as a guest. Sorrry for the confusion.

I concur with Paul on this.
What is the source of this question. ?