The Eiffel Tower Was Only Supposed To Stand For Twenty Years. How Long Did It Take To Build?

Algebra Level 1

The Eiffel Tower was the tallest structure in the world until 1930. If the first three images above were taken on March 1888, July 1888, and November 1888, which of the following dates is the most reasonable for the final picture of the completed tower?

December 1888 March 1889 January 1890 July 1889

12 solutions

Nurin Zunah
Jan 25, 2014

March 1888 + 4 months = July 1888

July 1888 + 4 months = November 1888

November 1888 + 4 months = March 1889

As a major bulk of construction is already over and remaining part to be constructed is small compared to the lower segments, I think it took lesser time than the previous quarters, maybe a month or two. So it might have been finished as early as January 1889!

santosh kumar - 7 years, 3 months ago

Santosh Kumar But that is offset by the tower being constructed higher in the air

Dylan Wedel - 3 years, 5 months ago

I think at that time huge machines were not available and hence work duration at height might be more than that of near the base

Amulyaratna Mishra - 5 years, 5 months ago

I'm just saying, the way the question is worded, and knowing the tower still stands today, the most reasonable date for a photo of a completed tower is taken should be the one that's closest to now. We don't know if construction was halted for a few months, which would rule out March 1889 from being the "correct" answer, and possibly many others. Therefore, the most recent date, to me, is the most reasonable solution.

Bango Skank - 4 years, 10 months ago

I still think a completed photo would be one that is closest to present day

Victor Adetunji - 1 year ago

I forget the month in number

Lego K - 9 months, 2 weeks ago

Yoon Ho Seol
Apr 10, 2016

I always thought math questions like "Conclude the following numbers for series 1, 2, ?, ? ...?" were quite silly. I mean with the little initial condition the answer could be plus "3, 4", power "4, 8", fibonacci "3, 5", repetition "1, 2", ternary "10, 11" and so many others.

For actual estimation of construction time, there are a few things think about: rhythm of work, volume of material, height of construction and etc. Considering this question is not for bunch of construction managers, we could just think about the volume and the height. Granted it has three pictures but there are literally not enough information given to us. So assuming the least incomplex expectation of our questioner, the answer could be "4 months." But question like this should allow multiple answers due to unclear information given.

Same I agree. There are so many various factors coming into play that we shouldn't use architecture and buildings in such math questions.

Ishan Maheshwari - 4 years, 7 months ago

I agree. Even though there is a math pattern that fits, it doesn't necessarily mean that in the real world such a pattern exists. It depends on the availability of workers and resources and also there might be a few unexpected errors.

Ishan Maheshwari - 4 years, 9 months ago

Not only that, the height of the tower seemed to increase by more than 1/4 in the last frame. I thought for sure that this picture was taken after more work was done than was required to raise the tower's height by 1/4, leaving only one answer.

Andrei Rotenstein - 4 years, 8 months ago

The thing about this is that there is less to build towards the end, so of course, there will be more done in the same amount of time.

Kevin Shi - 2 years, 7 months ago

If you use logic, it is clear that there is only one answer. It is important to consider the real-life aspect and to "estimate" because you will not always have all the information you require!

Raivat Shah - 3 years, 2 months ago

Sanjeev Mishra
Jan 25, 2014

The length of the tower is increasing at a uniform rate with time. It seems that after every 4 month the tower is $\frac14$ completed. Therefore, it would take four such intervals to complete the full tower, implying that it will be completed around March 1889.

Plus 4 months intervals. March OF 1889 would be the riht date.

Florentino Mortera - 7 years, 4 months ago

absolutely right calculation

Syeda Maryam Khalid Mannat - 7 years, 4 months ago

hmmmmm I think there is another stage b/w completion and the third picture bcoz there is another joint b/w final and the third picture from first two pictures we can easily detect that the constructors were working as per joints so, I think July 1889 is the right one.

Rehmat Ullah - 7 years, 3 months ago

Can't they just ad well have taken that last photo in 1890? Or 1891? Years after the tower has been completed?

Bango Skank - 4 years, 10 months ago

y the sum of masses of nucleons is less than the mass of nucleus in nuclear fussion reaction?????????

Uzair Akbar - 7 years, 3 months ago

Anonymous1 Assassin
May 24, 2021

no ones gonna see this because i am in the future, but all the months are three apart.

Jenson Chong
Dec 10, 2020

March 1888 + 4 months = July 1888

July 1888 + 4 months = November 1888

November 1888 + 4 months = (March 1889)

Don Weingarten
Feb 3, 2019

The pictures show approximately even intervals, assuming construction was at a uniform rate. In reality, the base would take longer to construct than would the higher part, as the structure narrows, involving less metal, the higher it goes. But the problem is only soluble if we make the assumption that each step takes the same amount of time, roughly. In this case, the interval is four months, and four months from November 1888 is March 1889.

Malcolm Parsons
May 28, 2018

The pattern is March July November then in 1889 March.

A Former Brilliant Member
Jan 24, 2018

Despite there's a pattern of dates, history DOES show that the final picture was taken March 1889.

Irina Stanciu
Jan 6, 2017

The difference between the pictures is always 4 months so the answer is March 1889

Hadia Qadir
Aug 30, 2015

March 1888 + 4 months = July 1888 July 1888 + 4 months = November 1888 November 1888 + 4 months = March 1889

I have a genuine doubt, as shown in the figure the tower tapers towards the top and therefore I think the workers should take lesser time to build the tower so from my point of view it should be around december or November can anyone explain please.

Swayam Chube - 5 years, 3 months ago

Beta 27
Aug 6, 2015

March 1888....July 1888....November 1888.... ? *July 1888 - March 1888 = 4 months *November 1888 - July 1888 = 4 months

So, ? = November 1888 + 4 months = March 1889

Atika Samiha
Aug 6, 2015

The Eiffel Tower is seen here in dividing into 4 equal divisions,and the time needed for making each division is 4 month.so it will take 4 months from the 3rd divisions to complete the whole tower.

The Eiffel Tower Was Only Supposed To Stand For Twenty Years. How Long Did It Take To Build?

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