Please help me with a 2 min approach to this problem. I have written a page on my rough work book but still not able to get an answer. I searched on the forum and could not understand the explanations.
Thanks
For the students in class A, the range of their heights is r
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Range = greatest - least.melguy wrote:For students in class A, the range in height is r and the greatest height is g. For students in class B, the range in height is s and the greatest height is h. Is the least height in class A greater than the least height of students in class B?
1) r<s
2) g>h
Thus:
Least = greatest - range.
In class A, least = greatest - range = g-r.
In class B, least = greatest - range = h-s.
If the least height in A is greater than the least height in B, we get:
g-r > h-s
g+s > h+r.
Question rephrased: Is g+s > h+r?
Statement 1: r < s
No information about g or h.
INSUFFICIENT.
Statement 2: g > h
No information about r or s.
INSUFFICIENT.
Statements combined:
Inequalities can be ADDED TOGETHER.
When we add, the < > must face the SAME DIRECTION in each inequality.
To match g > h in statement 2, rephrase r < s in statement 1 as s > r.
Adding together g > h and s > r, we get:
g+s > h+r.
SUFFICIENT.
The correct answer is C.
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Please check the solution as attachedmelguy wrote:Please help me with a 2 min approach to this problem. I have written a page on my rough work book but still not able to get an answer. I searched on the forum and could not understand the explanations.
Thanks
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Given: For the students in class A , the range of their heights is r cms and the greatest height is g cms.For the students in class A , the range of their heights is r cms and the greatest height is g cms. For the students in class B, the range of their heights is s cms and the greatest height is h cms. Is the least height of the students class A greater than the least height of the students in class B?
1) r < s
2) g > h
Range = greatest height - least height.
Rearrange this to get: least height = greatest height - range.
So, for class A, the least height = g - r
Given: For the students in class B, the range of their heights is s cms and the greatest height is h cms.
So, for class B, the least height = h - s
Target question: Is the least height of the students class A greater than the least height of the students in class B?
We can rephrase this as...
REPHRASED target question: Is h - s < g - r
Since it's often easier to deal with sums than with differences, let's rephrase the target question one more time by taking h - s < g - r and adding s and r to both sides to get...
RE-REPHRASED target question: Is h + r < g + s
Perfect!! Now that we've rephrased the target question, this question is relatively easy to solve.
Aside: We have a video with tips on REPHRASINGthe target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Statement 1: r < s
Since we have no information about h and g, we cannot answer the RE-REPHRASED target question with certainty.
So, statement 1 is NOT SUFFICIENT
Statement 2: g > h
Since we have no information about r and s, we cannot answer the RE-REPHRASED target question with certainty.
So, statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
IMPORTANT: If we have two inequalities with the inequality symbols FACING THE SAME DIRECTION, we can add them.
Statement 1: r < s
Statement 2: h < g [I rewrote the inequality so that it's facing the same direction as that in statement 1]
ADD the inequalities to get: h + r < g + s
Perfect!! Since we can answer the RE-REPHRASED target question with certainty, the combined statements are SUFFICIENT
Answer = C
Cheers,
Brent
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We are given that for the students in class A, the tallest student is g cm and the range in heights is r cm. If we let a = least height in class A, we can create the following equation:For the students in class A, the range of their heights is r centimeters and the greatest height is g centimeters. For the students in class B, the range of their heights is s centimeters and the greatest height is h centimeters. Is the least height of the students in class A greater than the least height of the students in class B?
(1) r < s
(2) g > h
g - r = a
We are also given that for the students in class B, the tallest student is h cm and the range in heights is s cm. If we let b = least height in class B, we can create the following equation:
h - s = b
We need to determine whether the height of the shortest student in class A is greater than that of the shortest student in class B.
That is, we need to determine whether a > b or whether g - r > h - s.
Statement One Alone:
r < s
Since we don't know anything about g and h, we cannot determine whether g - r > h - s.
Statement Two Alone:
g > h
Since we don't know anything about r and s, we can't determine whether g - r > h - s.
Statements One and Two Together:
From the two statements, we know r < s and g > h. We can multiply both sides of r < s by -1 (don't forget to switch the inequality sign) to get: -r > -s.
Adding the two inequalities gives us:
(g > h)
+ (-r > -s)
g - r > h - s
Since we have determined that g - r IS GREATER than h - s, we have answered the question.
Answer: C
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Hi All,
This DS question is more about patterns and relationships between variables than about math skills.
Class A:
Range of heights = R
Max height = G
Class B:
Range of heights = S
Max height = H
We're asked if the LEAST height of Class A > LEAST height of Class B. This is a Yes/No question. To figure out the LEAST height, we're going to need to understand the relationship between the Max height and the range for each class.
Fact 1: Tells us that the Range for Class A < Range for Class B. There's nothing here about the Max heights though.
Fact 1 is INSUFFICIENT
Fact 2: Tells us that the Max height for Class A > Max height for Class B. There's nothing here about the ranges though.
Fact 2 is INSUFFICIENT
Combining Facts:
We know that Class A has a HIGHER Max height and a LOWER Range than Class B. By definition, that would mean that the LEAST height for Class A was greater than the Least height for B (since Class A's heights are "closer together" than Class B's). The answer to the question is YES.
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
This DS question is more about patterns and relationships between variables than about math skills.
Class A:
Range of heights = R
Max height = G
Class B:
Range of heights = S
Max height = H
We're asked if the LEAST height of Class A > LEAST height of Class B. This is a Yes/No question. To figure out the LEAST height, we're going to need to understand the relationship between the Max height and the range for each class.
Fact 1: Tells us that the Range for Class A < Range for Class B. There's nothing here about the Max heights though.
Fact 1 is INSUFFICIENT
Fact 2: Tells us that the Max height for Class A > Max height for Class B. There's nothing here about the ranges though.
Fact 2 is INSUFFICIENT
Combining Facts:
We know that Class A has a HIGHER Max height and a LOWER Range than Class B. By definition, that would mean that the LEAST height for Class A was greater than the Least height for B (since Class A's heights are "closer together" than Class B's). The answer to the question is YES.
Final Answer: C
GMAT assassins aren't born, they're made,
Rich