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## hey rc

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frank1 Legendary Member
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Thu Nov 25, 2010 8:59 am
mundasingh123 wrote:
Farther distance from the peak means more layers of air (with different temperature and pressure or same temperature and pressure ) ? we need to clarify this.When its already mentioned that refraction takes place due to temperature and pressure change , we know that humid air means temperature and pressure change .This makes use of info given in passage itself and no outside knowledge , does it?
I think you mean D is answer.
But i think the case is which is more right
Both C and D are right.Even B is not incorrect.
but i think C is more right
see this line as well
Line 33-38 from the passage
To reduce refraction errors, the Chinese team carried in sea level to within five to twelve miles of Everest’s
summit, decreasing the amount of air that light passed through on its way to their theodolites

As per D measuring was done through ballon,we can still attack it.
So,C is more clear and less controversial than D so i think C wins

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Rezinka Master | Next Rank: 500 Posts
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Fri Dec 03, 2010 10:52 pm
OA please

mundasingh123 Legendary Member
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Sat Dec 11, 2010 1:45 pm
DanaJ says its C

maddy2u Senior | Next Rank: 100 Posts
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Mon Dec 20, 2010 1:49 am
maihuna wrote:
In 1975 Chinese survey teams
remeasured Mount Everest, the highest
of the Himalayan mountains. Like the
Line British in 1852, they used the age-old
(5) technique of “carrying in” sea level:
surveyors marched inland from the
coast for thousands of miles, stopping
at increments of as little as a few feet
to measure their elevation, and mark-
(10) ing each increment with two poles.
To measure the difference in elevation
between poles, surveyors used an
optical level-a telescope on a level
base-placed halfway between the
(15) poles. They sighted each pole, reading
off measurements that were then
used to calculate the change in elevation
over each increment. In sight of
the peaks the used theodolites-
(20) telescopes for measuring vertical and
horizontal angles-to determine the
elevation of the summit.
The Chinese, however, made
efforts to correct for the errors that
(25) had plagued the British. One source
of error is refraction, the bending of
light beams as they pass through air
layers of different temperature and
pressure. Because light traveling.
(30) down from a summit passes through
many such layers, a surveyor could
sight a mirage rather than the peak
itself. To reduce refraction errors, the
Chinese team carried in sea level to
(35) within five to twelve miles of Everest’s
summit, decreasing the amount of air
that light passed through on its way to
their theodolites. The Chinese also
launched weather balloons near their
(40) theodolites to measure atmospheric
temperature and pressure changes
to better estimate refraction errors.
Another hurdle is the peak’s shape.
When surveyors sight the summit.
(45) there is a risk they might not all
measure the same point. In 1975
the Chinese installed the first survey
beacon on Everest, a red reflector
visible through a theodolite for ten
(50) miles, as a reference point. One
more source of error is the unevenness
of sea level. The British
assumed that carrying in sea level
would extend an imaginary line from
(55) the shore along Earth’s curve to a
point beneath the Himalaya. In
reality, sea level varies according
to the irregular interior of the planet.
The Chinese used a gravity meter to
correct for local deviations in sea level.
-------------------------------------------------------------------------------------------------------
Q32
It can be inferred from the passage that
refraction would be most likely to cause
errors in measurements of a mountain’s
elevation under which of the following
conditions?
A. When there are local variations in sea
level --> Not mentioned in this part of the argument.
B. When light passes through humid air --> only temperature and pressure changes, humid is not part of the scope
C. When theodolites are used relatively far

from the mountain peak. -- > looks good as more distance means increased likelihood of pressure changes
D. When weather balloons indicate low air
temperature and pressure. --> only pressure changes affect the balloons. Low pressure doesn't
E. When sea level has been carried in to
Within five to twelve miles of the summit.-- Not in this part of the argument.
Answer must be C . Please post OA

anirudhbhalotia Master | Next Rank: 500 Posts
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Tue Dec 21, 2010 4:56 am
One source
of error is refraction, the bending of
light beams as they pass through air
layers of different temperature and
pressure. Because light traveling.
(30) down from a summit passes through
many such layers, a surveyor could
sight a mirage rather than the peak
itself.

This is tough....none of the answer choices seem to direct refer to the passage above.

Can some one solve and explain the same?

maddy2u Senior | Next Rank: 100 Posts
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Tue Dec 21, 2010 11:09 am
anirudhbhalotia wrote:
One source
of error is refraction, the bending of
light beams as they pass through air
layers of different temperature and
pressure. Because light traveling.
(30) down from a summit passes through
many such layers, a surveyor could
sight a mirage rather than the peak
itself.

This is tough....none of the answer choices seem to direct refer to the passage above.

Can some one solve and explain the same?
See my explanation on top . Since more distance means more chances for refraction to cause errors..

myavatar Newbie | Next Rank: 10 Posts
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Mon Feb 21, 2011 11:24 am
C for me too...There were certain assumptions though!!

I was not 100% sure but I went with this by process of elimination.

nasir Senior | Next Rank: 100 Posts
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Sat Jun 18, 2011 11:22 am
while reading the passage i thought i would answer any question, but this inference question made me read the passage two more times.... and still i had to guess... But i did chose C

tar_ac Newbie | Next Rank: 10 Posts
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Sun Aug 07, 2011 8:48 am
I did answer C. What is OA?

mzkfrk Junior | Next Rank: 30 Posts
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Thu Aug 18, 2011 8:55 am
C for me... B is also not incorrect... but C is the most obvious answer here.... remember , we need the "better" answer...

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killer1387 Legendary Member
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Fri Aug 19, 2011 7:55 am
C +1 ans as said earlier its obvious one so better than B

saketk Legendary Member
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Thu Sep 08, 2011 4:45 am
Quote:
To reduce refraction errors, the
Chinese team carried in sea level to
(35) within five to twelve miles of Everest’s
summit, decreasing the amount of air
that light passed through on its way to
their theodolites.
I thought this one is pretty straight - the answer can only be C. Read the lines.
It is clearly mentioned that to reduce the refraction Chinese kept the distance between 5 to 12 miles.

It cannot be D because we cannot infer that what type of weather and temperature cause refraction. Also the passage is talking about the 'CHANGE' in temp and weather.
Hope it is clear

parul9 Master | Next Rank: 500 Posts
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Tue Oct 11, 2011 8:32 am
IMO C

A148507 Newbie | Next Rank: 10 Posts
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Fri Jan 06, 2012 5:02 am
IMO c

Sharma_Gaurav Master | Next Rank: 500 Posts
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Sun Jan 08, 2012 12:40 pm
between C and D , but i selected option D. . total time taken = 3 min 43 seconds.
Question asks refraction error will occur most likely - ?
logical conclusion is " only when the light beam encounter many different layers of temp and pressure changes.
What is the distance of peak to the telecsope is too far but the temp and pressure is constant and there is no change . We do not know about this in C answer choice.

BUT as choice D states - if ballons indicated Low temp and pressure ( actually meaning lower than the present value ) -> indicating change , and hence will definitely cause refraction errors.
Hence i will go with option D .
Experts please reply tho this

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