The range for a list of measurements equals the greatest measurement

[quote="Sallyzodiac"]The range for a list of measurements equals the greatest measurement minus the least measurement. The two lists of measurements, \(X\) and \(Y\), combined consist of 30 measurements with a range of 25. What is the range for the measurements in list \(X\)?

1) The range for the 12 measurements in list Y is 20.

2) List X consists of 18 measurements.

answer to this question is E as both statements are not sufficient to tell you the answer

statement 1 tells that The range for the 12 measurements in list Y is 20 but that tell cannot tell you the range of x
take lowest number in list y= 1 and highest 21 and take all the nos in list x as 26. That will give you range of x =0
take lowest number in list y 1 and highest 21 and take lowest number in list x= 22 and highest =26 .That will give you range of x =4
two different answers so the statement is not sufficient.

statement tells only about the nos in list x but no additional information so not sufficient.

by combining both statements we are not able to get any answer.

So we are given 2 lists, X and Y and we are given that the
1. the total number of measurements is 30. X(n) + Y(n) = 30.
2. Largest measurement - Smallest Measurement = 25

But we are not told the number of measurements in either X or Y. We also don't know whether the largest of smallest measurement of the combined range belongs to X or Y.

We need to find the largest measurement of X and the smallest measurement of X for our answer.

1) 1) The range for the 12 measurements in list Y is 20.
Okay so we know that Y has 12 measurements, therefore X has 18. And we know the Y(largest)-Y(smallest) = 20 INSUFFICIENT

2) List X consists of 18 measurements.
We are told the X consists of 18 elements. We already figured this out in Statement 1 as well. It again does not tell us anything further. INSUFFICIENT

Answer is E

Here There are 30 measurements in x and y.
Range of 30 measurements is 25.
Range of x=?
First of all we need to know the elements that are present in x.

Statement 1:
From 1 we got to know that y has 12 measurements and x has 18.
Now Y has range 20:
we don't know what are the elements that make the range 25 overall and we don't even know the elements in x to find the range of x.

Statement 2:
Same problem as A in statement 2.we don't know the elements.

From 1+2.
we don't know any extra information.
So, the Answer is E

Lets say, the least number from the 2 lists is x. Then the biggest number from 2 lists will be (x + 25).
Statement 1: We cannot find the biggest and the smallest measurement in X from the given information. So, we cannot find the range of X. Hence, Insufficient.
Statement 2: No of measurements in list X doesn’t alone provide us with the range of X. Hence, Insufficient.
Statement 1 & 2 together: Information given in both the statement doesn’t help us in finding the range of X unless we are given that the smallest and the largest number of both the lists lie in X. Hence, Insufficient.

Let’s say, the least number from the 2 lists is x. Then the biggest number from 2 lists will be (x + 25).
Statement 1: We cannot find the biggest and the smallest measurement in X from the given information. So, we cannot find the range of X. Hence, Insufficient.
Statement 2: No of measurements in list X doesn’t alone provide us with the range of X. Hence, Insufficient.
Statement 1 & 2 together: Information given in both the statement doesn’t help us in finding the range of X unless we are given that the smallest and the largest number of both the lists lie in X. Hence, Insufficient.

Hi Sallyzodiac,

I feel like I am going crazy trying to solve this easy problem but am getting stuck. Could someone provide a detailed step by step method for solving this? Thank you so much!

Dear Bunuel,

Could you please shed some light here

To get the range of the list X , we need the maximum value and the minimum value in the list.

From statement 1 , we know the range of 12 measurements in list Y . So , if the first measurement is 100 then the last measurement is 120. But we dont know anything about the maximum or the minimum value in the list Y.

From statement 2 also , we don't know anything about the maximum or the minimum value in the list X.

Taking both together , we still don't know anything about the maximum or the minimum value of the list X.

Option E is the answer.

PLease give me KUDO s if you liked my answer.

Dear Bunuel ,

Please tag this question --- GMATPREP EP6


Best !!
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Done. Thank you!
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say, max and min of X:
Xmin, Xmax

say, max and min of Y:
Ymin, Ymax

Question gives, Ymax - Xmin = 25.
Question is asking, Xmax - Xmin = ?

(1) The range for the 12 measurements in list Y is 20.
First of all, this does not say that the number of measurements of Y is 12. Y can have 15 measurements, but range of 12 of them can be 20.
Even if you suppose that the number of measurements of Y is 12, this gives you:
Ymax - Ymin = 20
NOT SUFF.

(2) List X consists of 18 measurements.
does not add much to find out Xmax, Xmin.
NOT SUFF.

(1) + (2)
Now we are sure that the number of elements of Y is 12, and that of X is 18.
we can now say Ymax - Ymin = 20.
However, not possible to find out Xmax - Xmin.
For example,
Keep in mind that Ymax - Xmin = 25.
- Ymax = 30, Ymin=10, Xmin=5. We dont know Xmax (can be 10 or 15 or something).
NOT SUFF.