Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Grab 20% off any Target Test Prep GMAT Focus plan during our Flash Sale. Just enter the coupon code FLASH20 at checkout to save up to $320. The offer ends on Tuesday, April 30.
Ready to conquer GMAT's toughest Data Insights questions? Unlock the secrets of Graphical Interpretation & Two-Part Analysis with our expert-led webinar! Limited seats!
We present a collection of 30 GMAT Focus practice questions covering Problem Solving, Data Sufficiency, Data Insights, and Critical Reasoning. Take this GMAT practice quiz live with peers, analyze your GMAT study progress, and more.
n this GMAT experience talk show, we talk to Tavishi, a young MBA aspirant from India who recently scored 725 in her latest GMAT Focus exam. It’s a 99.9 percentile score on new GMAT Focus edition and she achieved this feat in her first GMAT attempt.
What do András from Hungary, Conner from the United States, Giorgio from Italy, Leo from Germany, and Saahil from India have in common? They all earned top scores on the GMAT Focus Edition using the Target Test Prep course!
In this webinar, Rajat Sadana, GMAT Club’s #1 rated expert will help you create a personalized study plan so that each one of you can visualize your journey to a top GMAT Focus Score.
In 1975 Chinese survey teams remeasured Mount Everest, the
[#permalink]
04 Jul 2008, 13:08
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 B. When light passes through humid air C. When theodolites are used relatively far from the mountain peak. D. When weather balloons indicate low air temperature and pressure. E. When sea level has been carried in to Within five to twelve miles of the summit.
Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Re: In 1975 Chinese survey teams remeasured Mount Everest, the
[#permalink]
04 Jul 2008, 13:27
IMO B. Humidity will cause more refraction. Moreover humidity varies as per altitude so more chances of refraction.
I discount another close call D, because indication of low temperature and pressure does not itself mean there is variations in temperature and pressure.
Re: In 1975 Chinese survey teams remeasured Mount Everest, the
[#permalink]
04 Jul 2008, 13:45
Quote:
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 B. When light passes through humid air C. When theodolites are used relatively far from the mountain peak. D. When weather balloons indicate low air temperature and pressure. E. When sea level has been carried in to Within five to twelve miles of the summit.
I’d pick C.
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.
Inference: Closer to the mountain -> smaller errors. Farther from the mountain -> bigger error.
Also, I think B is not right because it is not the humid air per se that could spoil the measurements, but rather many ‘layers of different temperature and pressure’.
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
gmatclubot
Re: In 1975 Chinese survey teams remeasured Mount Everest, the [#permalink]