A certain economic indicator is proportional to the square

Question

A certain economic indicator is proportional to the square of the unemployment rate. If the unemployment rate increases by 10 percent, then the indicator will increase by

A. 1%
B. 10%
C. 11%
D. 21%
E. 100%

ankitgoswami · Accepted Answer

EI = p*(UR)^2 where p is a constant

Now unemployment rate becomes 1.1UR 
So

EI = p*(1.1UR)^2
 = p*(1.21UR)

An increase of 21%

Ans  D

Posted from my mobile device

DanTheGMATMan · Answer

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JeffTargetTestPrep · Answer

If the GMAT tells us that a variable is proportional to another variable, then the two variables are directly proportional to each other. If two variables are directly proportional, then their ratio is constant.

The unemployment rate’s 10% increase corresponds to a factor of 1.1. Let x be the factor by which the indicator will change, and we have:

e/u^2 = ex/(1.1u)^2

e/u^2 = ex/(1.21u^2)

1 = x/1.21

x = 1.21

A factor of 1.21 corresponds to a 21% increase.

Answer: D

Abhishek009 · Answer

+10 + 10 + \frac{(+10)(+10)}{100} = 21 , Answer must be (D)

unraveled · Answer

A certain economic indicator is proportional to the square of the unemployment rate. If the unemployment rate increases by 10 percent, then the indicator will increase by

A. 1%
B. 10%
C. 11%
D. 21%
E. 100%

Let rate is 10% which increases by 10% which eventually becomes 10 + 10*.1 = 11%.
Initially the indicator was 100 which became 100(1+11*11) = 121
i.e. 21%

Answer D.

ruis · Answer

Does anyone know any similar exercises of this type and of inverse proportion to practice?

DanTheGMATMan · Answer

Directly proportional-  P=Ke where K is a constant. Basically always choose numbers for these to get a K value and then plug back in:

https://www.youtube.com/watch?v=yqu14Jwm1Fo

A_Nishith · Answer

Let unemployment rate be represented as (U) & Economic Indicator be represented as (I).
As per question;  I = K*U^2   ----- where K is proportionality constant.
=> K = I/ U^2 ----- Eq.1

Given that unemployment rate (U) increased by 10% =>  U changed to 1.1U  . Let new Unemployment rate be Ux & new Index be Ix.
Now, we have:
Ix= K* Ux^2
=> Ix = K * {1.1U}^2
=>  Ix = K * 1.21 U^2

=> K = Ix / 1.21 U^2 -------- Eq.2

Equating Eq.1 & Eq.2,

A factor of 1.21 corresponds to a 21% increase.
Answer: D

hkalabdu · Answer

First step find the K constant:

EI = K(Constant) * (UR)^2.

Lets assume EI is 10. UR is also 10.

K = 10/100 = 1/10.

Thus EI = 1/10 * (11)^2 = 121/10 = 12.1.

Therefore the Constant increased by 12.1/10 = 21.1%

mcelroytutoring · Answer

Attached is a visual that should help.

Vordhosbn · Answer

Directly proportional to square of unemployment rate (UR) means: Indicator = k * (UR)^2

Now we can make our job here easier by assigning values. Dan's video focuses on the wrong thing really, and at end he kind of brushes over his not so great values. The question is not at all about the constant of proportionality (i.e, k). So we assign it the value of 1, and let UR be 10.

indicator before increase is: 1 * 100 = 100

increase UR by 10 we get 11.

the new indicator is:
1 * 11^2 = 121

100 -> 121 is a 21% increase.

Max377 · Answer

We can also plug in numbers - as 20 for the Unemployment Rate; if it raises by 10%, which is to - it will become 22, in this case making the previous 400 of the indicator 484, which is exactly 121 percent of the 400, which indicates a 21 percent increase

nandini14 · Answer

How did you make it 484 from 400?

egmat · Answer

nandini14

Here's how this works:

The indicator is proportional to the  SQUARE  of the unemployment rate.

Breaking Down the Calculation: 
When we chose unemployment rate =  20 :
 
 Original indicator =  20^2 = 400

When unemployment increases by  10% , it becomes  22 :
 
 New indicator =  22^2 = 22 	imes 22 = 484

That's how we get from  400  to  484  - we're  squaring  the new unemployment rate!

Why This Works:

Since the problem states the indicator is "proportional to the square" of unemployment, this means:

Indicator =  k 	imes U^2  (where  k  is some constant) 
 When  U = 20  gives indicator =  400 , we know  k = 1   
 
 So when  U = 22 , the indicator must be  1 	imes 22^2 = 484

Remember: "Proportional to the square" means you must square the new value, not just scale it proportionally!

Bunuel · Answer

He squared the unemployment rate because the indicator is proportional to the square of that rate. If the rate is 20, then the indicator is 20^2 = 400. A 10% increase makes the rate 22, so the indicator is 22^2 = 484. That’s where 484 comes from.

A certain economic indicator is proportional to the square

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A certain economic indicator is proportional to the square

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