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If a lumberjack crew needs to secure a safety zone for cutting down the trees, how far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimeter is minimized? The first tree is the highest one.

1. The height of the first tree is 50m. 2. Currently the distance from the barrier to the top of the tree is 70 meters.

(C) 2008 GMAT Club - m07#18

* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient * Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient * BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient * EACH statement ALONE is sufficient * Statements (1) and (2) TOGETHER are NOT sufficient

S1 tells us that the tree, if cut down, will hit the ground no farther than 50 meters away from its origin. It is sufficient as we know that the barrier has to be at least 55 meters away. S2, without the height of the tree, is insufficient. ********************************************************************

We can find the from second one as well. say hieght of tree is X . Then X^2 + (X+5)^2 = 70^2

Yes, your answer is correct if you are considering the first tree longest. What if the 2nd tree is longer than the 1st tree. Suppose the distance between both the tree is less than the difference between their heights. In that case both the statements are useless and answer is (E).

abhaypratapsingh wrote:

A lumberjack crew needs to secure a safety zone for cutting down the trees. How far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimieter is minimized?

1. The height of the first tree is 50m 2. Currently the distance from the barrier to the top of the tree is 70 meters

* Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient * Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient * BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient * EACH statement ALONE is sufficient * Statements (1) and (2) TOGETHER are NOT sufficient

S1 tells us that the tree, if cut down, will hit the ground no farther than 50 meters away from its origin. It is sufficient as we know that the barrier has to be at least 55 meters away. S2, without the height of the tree, is insufficient. ********************************************************************

We can find the from second one as well. say hieght of tree is X . Then X^2 + (X+5)^2 = 70^2

If a lumberjack crew needs to secure a safety zone for cutting down the trees, how far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimeter is minimized? The first tree is the highest one.

The height of the first tree is 50m. Currently the distance from the barrier to the top of the tree is 70 meters.

Stmt 1 we all know is suff. Stmt 2:We know here that the first tree is the longest. So,x^2+x^2=70^2 and so x=ht of the tree can be found out.. IMO: D _________________

How did you come up with that equation? What is that equation based on? Yes, we know that the first tree is the longest one. However, we still can't find its height with only that info.

Do you agree?

tejal777 wrote:

Stmt 1 we all know is suff. Stmt 2:We know here that the first tree is the longest. So, x^2+x^2=70^2 and so x=ht of the tree can be found out.. IMO: D

I second this doubt. In the question we are given the barrier perimeter is minimized. If we place the barrier away more than 5 m then we cant have the minimum perimeter. So, statement 2 is also sufficient. OA should be D.

Please comment.

dzyubam wrote:

How did you come up with that equation? What is that equation based on? Yes, we know that the first tree is the longest one. However, we still can't find its height with only that info.

Do you agree?

tejal777 wrote:

Stmt 1 we all know is suff. Stmt 2:We know here that the first tree is the longest. So, x^2+x^2=70^2 and so x=ht of the tree can be found out.. IMO: D

S2 can't be sufficient on its own. Suppose the first tree is not the highest one. If the tree next to it is higher than the first one, it will need a bigger safety zone. _________________

I think we already have this condition in the question:

If a lumberjack crew needs to secure a safety zone for cutting down the trees, how far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimeter is minimized? The first tree is the highest one.

dzyubam wrote:

S2 can't be sufficient on its own. Suppose the first tree is not the highest one. If the tree next to it is higher than the first one, it will need a bigger safety zone.

It's not stated in the question stem or S2 that the current position of the barrier follows the rule. We can't construct that equation unless we know exactly that the position of the barrier follows the rules. Moreover, we can't be sure that distance of 70 meters is measured to the tree closes to the barrier.

What do you think?

ykaiim wrote:

I think we already have this condition in the question:

If a lumberjack crew needs to secure a safety zone for cutting down the trees, how far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimeter is minimized? The first tree is the highest one.

dzyubam wrote:

S2 can't be sufficient on its own. Suppose the first tree is not the highest one. If the tree next to it is higher than the first one, it will need a bigger safety zone.

I dont think we need that much reasoning. If I go with your point, then even S1 can't bring the solution.

Lets disect the question stem: If a lumberjack crew needs to secure a safety zone for cutting down the trees, how far from a given tree should the safety barrier be put up so that it is at least 5 meters away from the danger area, and the barrier perimeter is minimized? The first tree is the highest one.

1. We need to place the barrier at >=5 away from the danger zone. 2. If we have to make the barrier perimeter minimum then, what I understand, the barrier has to be placed at no more than 5m away from danger zone. So, S2 becomes just like S1. So, we can solve for the distance. _________________