A geometry problem by Vaibhav Raj

Geometry Level 2

If the sides of a square are increased by 1%, then by what percent will the area of this square be increased?

1% 1.01% 2.01% 3.01%

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16 solutions

Pigeon Gymnastic
Aug 6, 2014

Let side = 100. Increase 1% =101. Area = 10201 = 2.01% increased

Cool. Thank you. That is very interesting.

Corey Malecka - 6 years, 9 months ago

what a nice move dudz

charlie milano - 6 years, 9 months ago

So good move

Sonam Damdul - 5 years, 4 months ago

Correct me If I'm wrong but I think the answer is none of the above. Let 100% be 100. The square of 100 is 10000. If you add 1%, and let it be 101 The square of 101 is 10201. (100) 10000/10201 = 98.0296% 100-98.0296 = 1.9704% 1.9704% is my answer, and it is not in the solution.

William Laureta - 6 years, 9 months ago

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you did it backwards. it should be 10201/10000 - 1 = 0.0201 = 2.01%

Inki Hong - 6 years, 9 months ago

They are asking increased square value in percentage. Comparing original square area value 10000. Increased square area 10201. Increased square area 201 higher. ( for 10000) to get in terms of hundred you can divide both value by 100. 10000/100=100 & 10201/100-102.01. here the increased percentage is 2.01

Parthi Ban - 6 years, 5 months ago

Let the side of square = x. Thus, area A= x^2. Now when side is increased by 1%, The new side is x+x/100 = 101x/100. Thus, the new area is , A'= (101x/100)^2 = 10201x^2 /10000. The area ratio = A'/A = 10201/10000. The percentage area ratio = A'/A * 100% = 10201/100 =102.01%. Thus percentage increased= A'/A * 100% - 100%= (102.01-100)% = 2.01%

T h i s p r o b l e m i s a p i e c e o f i c e c r e a m ! \large \color{#D61F06}This~problem~is~a~piece~of~ice~cream!

let A 1 A_1 be the area of the original square and A 2 A_2 be the area of the larger square, then

A 1 A 2 = 1 2 1.0 1 2 = 1 1.0201 \dfrac{A_1}{A_2}=\dfrac{1^2}{1.01^2}=\dfrac{1}{1.0201}

It follows that, A 2 = 1.0201 A 1 A_2=1.0201A_1

% i n c r e a s e d = ( 1.0201 1 ) ( 100 % ) = 2.01 % \%~increased=(1.0201-1)(100\%)=2.01\%

I did the same.

Marvin Kalngan - 1 year, 1 month ago
Sean Roberson
Aug 4, 2014

Let s s be the side length of this square. The new area of the square is ( 1.01 s ) 2 (1.01s)^2 , or 1.0201 s 2 1.0201s^2 . So, the answer is 2.01 % \boxed{2.01 \% } .

In problem it is written sides of a Sq . So I think it must be like this 1.01 (s)^2 Not whole bracket sq

satyajeet masurkar - 6 years, 10 months ago

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No, that is correct. The measure is s s and I'm scaling it by 1.01 1.01 , so I need to multiply the two.

Sean Roberson - 6 years, 10 months ago
Krishna Garg
Aug 27, 2014

Considering side increased by 1 % ,so area of 100 cm length of square will be 10000, get increased to 10201 that is 2.01 % Ans K.K.GARG,India

Since they are similar polygons,

A 1 A 2 = \frac{A_1}{A_2}= a 2 ( 1.01 a ) 2 \frac{a^2}{(1.01a)^2} = = 1 1.0201 \frac{1}{1.0201}

1.0201 A 1 = A 2 1.0201A_1=A_2

% i n c r e a s e d = increased= ( 1.0201 1 ) ( 100 ) = 2.01 (1.0201-1)(100)=2.01 %

Another way of attacking problems like this is to set a value for a, and the best value is 1, so we let the side of the original square to be 1 unit, then the larger side is 1.01(1) = 1.01 unit

area of original square = 1

area of bigger square = (1.01)^2 = 1.0201

% increased in area = (1.0201 - 1)(100) = 2.01%

Prasit Sarapee
Feb 19, 2016

Total area = 1.01 x 1.01 = 1.0201
Area increase 0.0201 = 2.01 %

Habtamu Muse
Dec 17, 2014

Let each side of the square is 1cm long. Then area of the square is 1cm sq. If we increase each side of the square by 1%, then each side of the square is 1.01cm resulting the area of the square to 1.0201cm sq. When we take the difference of the area of the square as a result of 1% increment on its each side, we get 0.0201. Simply putting these in percentile we get 2.01%.

I let the the sides of the smaller square equal 100, and the larger square equal 101. The area of the smaller square = 100 100 = 10,000. The area of the larger square = 101 101 = 10,201. The difference is 201. 201/10000 = .0201 or 2.01%.

Anna Anant
Dec 19, 2014

For 100 100(10000) it becomes 101 101(10201)

So, 10000 is increased by 201 1 is increased by 201/10000 100 is increased by 201*100/10000=2.01

Nehem Tudu
Dec 18, 2014

let side of the square be a side of the square increased by 1% so side becomes 1.01a area of the square becomes (1.01a)^2=1.0201a^2 area increased in %= ((a^2)-(1.0201a^2))*100/a^2=2.01%

Parthi Ban
Dec 18, 2014

Lets take side of square a is 100 and area is a^2. so 10000. If side increase by 1% is 101. so are 10201. Square without increase is 10000 & after increase is 10201. Difference 201(increased). To find percentage we have to get in term of hundred, for that we can remove two points in 10201/100(to get value in hundreds) it 102.01. Increased square value 2.01

Saiyam Bhatnagar
Sep 17, 2014

a= %inc in l b=%inc in b a+b+(a*b)/100

Moni Saxena
Aug 13, 2014

use a+a+(a.a/100) % where a= % increased

David Baker
Aug 9, 2014

If the square initially has a side length of 'A' then after the increase the side lengths are now (A+A/100). Initially, the square has an area of A^2, but after the increase the area is now (A+A/100)^2.

This means that after the increase the square now has an area of A^2 + (2A^2)/100 + (A^2)/10000. Now initially, the square had an area of A^2, therefore to find the increase as a decimal multiplier, divide through by A^2. This gives: 1+2/100+1/10000.

We now multiply this by 100 to get a value of the area of the new square as a percentage of the 'old square' size. Hence we get: 100%+2%+0.01%= 102.01%. The 'old square' was 100% so to find % increase we can simply subtract 100% from 102.01% , which is 2.01%.

Therefore 2.01% is the solution.

Jester De Vera
Aug 5, 2014

\frac { { S } { 2 } }{ { S } { 1 } } =\frac { { A } { 2 } }{ { A } { 1 } } \ *where;\quad { S } { 2 }={ 1.01(S } { 1 })\ { \left[ \frac { { 1.01(S } { 1 }) }{ { S } { 1 } } \right] }^{ 2 }=\frac { { A } { 2 } }{ { A } { 1 } } \ *cancel\quad { S } { 1 }\ { (1.01) }^{ 2 }=\frac { { A } { 2 } }{ { A } { 1 } } \ 1.0201({ A } { 1 })={ A }_{ 2 }\ \therefore \quad The\quad area\quad is\quad increased\quad by\quad 2.01%\quad of\quad the\quad original\ \ \

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