need explanation pls

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Source: — Data Sufficiency |

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by DanaJ » Sun Jul 05, 2009 6:42 am
1 is insufficient because we don't have any info about k and r.

2 is insufficient if you consider two examples:
a. r = 1, z = 3.6 and k = 12 - in this case:
r/2 = 0.5
z/3 = 1.2
k/4 = 3

The correct order would be r/2 < z/3 < k/4, which means that the answer to the question in the stem will be NO.

b. r = 3.2, z = 3.3 and k = 3.6 - in this case:
r/2 = 1.6
z/3 = 1.1
k/4 = 0.9

The correct order will be k/4 < z/3 < r/2 - so the answer to the initial question will be YES.

Since we get two conflicting answer depending on the numbers we chose, then 2 is insufficient as well.

There's a reason I chose 3 < z < 4 in both cases outlined at point 2 above. This is because the two examples also prove that both statements taken together are not sufficient, since in both instances we have z between 3 and 4, with r < z < k.

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Re: need explanation pls

by maihuna » Sun Jul 05, 2009 6:57 am
sanjib wrote:Are the numbersk/4,z/3 and r/2 in increasing order?
(1) 3 < z < 4
(2) r < z < k
Need help pls.
3k<4z<6r

for 2, if r=2, z=3, k =4
3k = 12, 4z=12, r = 12 so 3k=4z=6r
but for r=2, z=3.5, k =4, 3k=12, 4z=14, 6r=12

so two scenario. not sufficient

combining also does not work as for
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