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Re: A zoo has twice as many zebras as lions and four times as ma [#permalink]
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NickBass wrote:
GreenlightTestPrep wrote:
sandy wrote:
A zoo has twice as many zebras as lions and four times as many monkeys as zebras. Which of the following could be the total number of zebras, lions, and monkeys at the zoo?

Indicate all such totals.

A. 14
B. 22
C. 28
D. 55
E. 121


A zoo has twice as many zebras as lions
So, the ratio of zebras to lions = 2 : 1
Or we can write: Z : L = 2 : 1


There are four times as many monkeys as zebras
So, if Z = 2, then M = 8
In other words, M : Z : L = 8 : 2 : 1

So, one possible scenario is: 8 monkeys, 2 zebras and 1 lion (total = 11 animals)
Another possible scenario is: 16 monkeys, 4 zebras and 2 lions (total = 22 animals)
Another possible scenario is: 24 monkeys, 6 zebras and 3 lions (total = 33 animals)
Another possible scenario is: 32 monkeys, 8 zebras and 4 lions (total = 44 animals)
etc....

As we can see, the total number of animals must be a multiple of 11

Check the answer choices.....

B, D and E are multiples of 11

Answer: B, D, E

Cheers,
Brent



I read in a GMAT book that "There are four times as many monkeys as zebras" would mean Monkeys/4 = the number of zebras. So 4z=M.

Can you explain why that isn't the case here? I got the right answer, so I'm up to speed on the concept, but had to work through this clutter.


It does actually apply here as well. It is true that 4Z=M. We also know that Z=2L. Then substituting this into the former: 4(2L)=M --> 8L=M.
To work it out further in this manner: we know that Z=2L and there are L lions. So we add them all up:
8L + 2L + L = 11L
Therefore, the total number of animals should be a multiple of 11.
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Re: A zoo has twice as many zebras as lions and four times as ma [#permalink]
Why is the wording of this question so confusing to me?

twice as many zebras as lions: 2z = l
then, I thought
four times as many moneys as zebras: 4m = z

BUT, as many pointed out here that 4m = z is clearly wrong. Why the language is the same but 4m = z is not correct? The wording must have tricked me somehow. Can someone help?
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Re: A zoo has twice as many zebras as lions and four times as ma [#permalink]
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Twice as many zebras as lions so \(z : l = 2 : 1\)

Four times as many moneys as zebras = \(m : z = 4 : 1\) --- \(m = 4z\)

The nos are in proportion here. Twice as many zebras as lions means that for every lion there are two zebras.

So \(m : z : l = 8 : 2 : 1\)

Hence the answer will be multiple of \(11\).

mind wrote:
Why is the wording of this question so confusing to me?

twice as many zebras as lions: 2z = l
then, I thought
four times as many moneys as zebras: 4m = z

BUT, as many pointed out here that 4m = z is clearly wrong. Why the language is the same but 4m = z is not correct? The wording must have tricked me somehow. Can someone help?
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Re: A zoo has twice as many zebras as lions and four times as ma [#permalink]
z = 2L
=> L = z/2

m = 4z

total:
z + L + m
= z + z/2 + 4z
= 11z/2
= 11/2 * z

To make the total count an integer, the least value of z = 2

So, the total could be 11 or multiples of 11.

Ans: B, D, E
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Re: A zoo has twice as many zebras as lions and four times as ma [#permalink]
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