A group of entomologists estimates that the population of Insect Speci

Question

A group of entomologists estimates that the population of Insect Species X is decreasing at a constant rate of 10% per year, while the population of Insect Species Y is decreasing at a constant rate of 15% per year. Based on these estimates, in four years, the two species will have equal populations, rounded to the nearest million.

In the table below, identify a number for the current population of Insect Species X, in millions, and a number for the current population of Insect Species Y, in millions, that is consistent with the entomologists’ estimates.

Apt0810 · Answer

Population of Y/ Population of X

= (.9/.85)^4
~1.25

So Y = 565,X=450,per the options from the table

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ebdsc123 · Answer

Please somebody explain me the answer

my equation comes out to be (y/x)=3/2)

ebdsc123 · Answer

Please somebody explain me in detail

samarpan.g28 · Answer

Hi  ebdsc123 , let me help you.

Let us consider the current population of X is x and that for Y is y.
x is decreasing by 10% and y is decreasing by 15%. Therefore, after 4 years of decrement, x becomes x*(0.9)^4 ~ 0.66x and y becomes y*(0.85)^4 ~ 0.5y.
The above two values are equal as stated in the question. 0.66x=0.5y or, x/y=0.5/0.66=0.75.
Now, take some values from the options for x and y.
1. If x=450 and y=525 then x/y=0.85 ->way too much than 0.75.
2. If x=450 and y=565 then x/y=0.79 ->pretty close to 0.75.
Rest I think will not be close to 0.75. Therefore, x=450 and y=565.

I hope this helps.

Oppenheimer1945 · Answer

Population of Y/ Population of X

= (.9/.85)^4
~1.25

(770, 625) as well as (565,450) satisfies approximately.

A good ques stem but Not a good quality option setting.

mkeshri185 · Answer

I got 0.90^4 *x = 0.85^4 *y 
which is x = 0.78*y
then on putting y=770 x is very close to 600 then why (600 , 770) is not correct it is the closest answer

arushi118 · Answer

*x =  *y
where x and y are the initial values.

on solving we find that y/x = 1.256

A group of entomologists estimates that the population of Insect Speci

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Insect Species X	Insect Species Y	Current Populations (in millions)
		450
		525
		565
		600
		625
		770

GMAT Two-part Analysis (TPA) Questions

A group of entomologists estimates that the population of Insect Speci

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

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My Rewards