Electrical engineers have developed an energy-efficient type of light

Question

Electrical engineers have developed an energy-efficient type of light bulb that can replace the traditional incandescent bulb. The new bulb, known as the electronic lamp, operates by using a high frequency radio signal rather than the filament featured in incandescent bulbs. Although the electronic lamp currently costs 20 times as much as its traditional counterpart, its use will prove more cost effective in the long run. While a 100-watt incandescent bulb lasts 6 months if burned for 4 hours daily, a 25-watt electronic lamp used for the same amount of time each day lasts up to 14 years.

The argument above assumes that

A. the typical household use of a light bulb is approximately 4 hours a day

B. aside from its greater efficiency, the electronic lamp resembles the incandescent light bulb in most aspects

C. the type of light cast by the electronic lamp is different from that cast by an incandescent bulb

D. the price of electronic lamps will decrease as they are produced in increasingly greater quantities

E. a 100-watt incandescent light bulb does not provide significantly more light than a 25-watt electronic lamp

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sayan640 · Answer

E should be the answer. If 100 W bulb provides more light than the 25W electronic lamp , then we can't say 25 W electronic lamp will be more cost effective.

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Ranu2024 · Answer

@Bunnel :- please let me know why A is wrong.
If a household uses the light for 4 hrs/day its lifespan is for 6 months and again we need to purchase it. So on the longer run we won't save moneh whereas by using electronic lamps we could save it as its lifespan is for 14 yrs if used for same hrs. 
Kindly correct my rationale.

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ankitmahla · Answer

Why is option E correct. because even if the 100w bulb provide more light, the electronic lamp use can be proved to be more cost effective so the argument hold even in this case.

ankitmahla · Answer

GMATNinja  , can you explain this answer. Why is option E correct. because even if the 100w bulb provide more light, the electronic lamp use can be proved to be more cost effective so the argument hold even if this assumption is false.

Shwarma · Answer

Option E 
I was confused between these two of E and B
My understanding

1. The 20X expensive bulb will replace the OG, as it lasts long but the comparison is between 100 watt of with a 25 watt new in the study.

Negate B-> OG and new are different -> that is ok coz the discussion is NOT about similarity but how the new is better than efficient
Negate E--> 100 watt gives more light than 25 watt OG, then it by how much, how many more new do you need and how much more energy is that, the whole study and the conclusion about the efficiency can be broken. So it is E

Aashi108 · Answer

I think its incorrect because if the household use the 100 watts for 6 hours( instead of 4) it will last for less than 6 months. Similarly if they use the new 25 watt bulb for 6 hours, it will last for less that 14 years, assuming that they both work in the same capacity. It might end up that one might need 4, 25 watts unlike the single 100 watt bulb, thus no longer equally efficient. So IMO A, is incorrect and E seems to be the right answer. Not sure it this helps

Bunuel · Answer

KAPLAN OFFICIAL EXPLANATION:

E

Here we need to identify an assumption. The author attempts to demonstrate that the "electronic lamp" can replace the incandescent bulb (that's the conclusion) because although the electronic lamp now costs much more, it will prove more cost effective  in the long run  (that's a summary of the evidence). He backs up this claim with numbers: A 25-watt electronic lamp can last 28 times longer than a 100-watt incandescent bulb while costing only 20 times as much as the bulb (thaT's the-hard evidence). There's one factor missing from the equation, though, and that's the amount of light the electronic lamp supplies. For the numbers given to support the author's conclusion, the electronic lamp and the normal bulb must each throw about the same amount of light. Otherwise, we might need 15 lamps for every bulb; and if this were the case, the argument would be dead wrong. Unless we assume, as (E) says, that the light produced by the lamp and the bulb is approximately equal, the evidence is meaningless.

(A) isn't assumed because the figure  4 hours a day  doesn't have to represent typical household use; it need only provide a standard by which the lights can be compared. (B) is contradicted by the author. Since the electronic lamp operates by radio waves instead of a filament, it's clear that there are important structural aspects in which it differs from incandescent bulbs. (C) would actually make us doubt the reasonableness of the author's conclusion, so clearly it isn't assumed. If the electronic lamp is supposed to be a replacement for the incandescent bulb, its light should be similar to that produced by the bulb. (D) misconstrues why the electronic lamp is claimed to be cost effective in the long run-the point is that it lasts longer, not that it will become cheaper. The author is arguing that current electronic lamps are more cost effective, not that future lamps will be.

TathagataC · Answer

In the first line of the paragraph, it is written " Electrical engineers have developed an energy-efficient type of light bulb that can replace the traditional incandescent bulb." 
And now look at option E - a 100-watt incandescent light bulb does not provide significantly more light than a 25-watt electronic lamp.

Suppose the 100-watt incandescent light bulb provides more light than a 25-watt electronic lamp. In that case, it can be inferred that the electronic lamp cannot act as a substitute for the incandescent light bulb, then how will it ever replace the incandescent light bulb.

Dooperman · Answer

The argument is comparing two bulbs and talks about their cost and life. So if two things are comparable then the author must assume their output should also be comparable.

Hence E.

VerbalBot · Answer

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Electrical engineers have developed an energy-efficient type of light

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Electrical engineers have developed an energy-efficient type of light

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