patto wrote:
The airport's runways are too close to each other to allow simultaneous use of adjacent runways when visibility is poor, so the airport allows only 30 planes an hour to land in poor weather; in good weather 60 planes an hour are allowed to land. Because airline schedules assume good weather, bad weather creates serious delays.
Which one of the following is most strongly supported by the information above?
(A) In poor weather, only half as many planes are allowed to land each hour on any one runway at the airport as are allowed to land on it in good weather.
(B) When the weather at the airport is good it is likely that there are planes landing on two adjacent runways at any given time.
(C) If any two of the airport's runways are used simultaneously, serious delays result.
(D) Airlines using the airport base their schedules on the assumption that more than 30 planes an hour will be allowed to land at the airport.
(E) In good weather, there are few if any seriously delayed flights at the airport.
Note : This explanation is copied from MGMAT LSAT page :
Let's work Wrong to Right, as you suggested. Your inference is valid, by the way.
The information does support that adjacent runways are made available when the weather is good.
A) This is making a bit of a leap from overall airport capacity to specific runway capacity. We know that in poor weather, only half as many planes per hour are allowed to land at the airport as in good weather. But we can't necessarily extrapolate that each runway also has twice the capacity in good weather.
B) "it is likely"/"at any given time" are loaded phrases. We CAN infer that when the weather is good that at some point planes are landing on adjacent runways. But the idea that at any instant it is likely that two planes are landing is extreme. If 60 planes land per hour (but they're landing simultaneously on adjacent runways), you could potentially have 30 landings only take 30 minutes of that hour. The other 30 minutes wouldn't have any landings. This type of scenario would contradict what (B) is saying, but it's compatible with the information.
C) This actually goes AGAINST the gist of the paragraph. Using runways simultaneously promotes staying ON schedule, not serious delays.
D) This is reasonably supported. Why does bad weather create serious delays? It must be because airlines are assuming they can land more than 30 planes per hour.
E) "few if any" is a loaded phrase. Just because bad weather creates serious delays, we can't assume that good weather involves few or no delays.
Let me just give you a few thoughts about how we might read Inference more proactively.
With Inference questions, we're not necessarily going to try to predict the answer, but we SHOULD try to synthesize the information we read. Most correct answers are derived by combining two or more ideas in the information.
It's often helpful to ask yourself, especially if there are only 2 sentences, "what do I know based on combining sentence 1 and sentence 2? How do they relate to each other?"
Both sentences deal with weather conditions. Sentence 1 deals with use of adjacent runways. Sentence 2 deals with airlines schedules and delays.
Normally, the common thread to both sentences gives us a way to infer something about the one-off ideas.
The last sentence says that airline schedules are based on good weather (in the first sentence, 'good weather' is code for 'allowed to use adjacent runways / 60 planes per hour').
Bad weather creates delays. 'Bad weather' is code for 'use of adjacent runways is not allowed/ 30 planes per hour'.
So we can infer that we need to use adjacent runways / have more than 30 planes per hour in order to stay on schedule.
I think you were definitely on to the right scent, because (B) is essentially tempting you with that inference, but using language that's too precise and extreme. (D) is the safer version of that inference.