I12-07

Question

In a class of 20 students, the average weight of the students is 40 kg and the range is 10. However, the average weight increases to 41 when a new student joins the class in the new session.
 
Based on the above information, select for  Maximum range  the maximum possible range of the weight of the new class and for  Minimum range  the minimum possible range of the weight of the new class.

DailyDays · Answer

Hi everyone, do you have any similar questions to test this knowledge? It'd be much appreciated!

Bunuel · Answer

Check these PS questions: https://gmatclub.com/forum/the-average- ... 73362.html https://gmatclub.com/forum/the-range-of ... 29434.html https://gmatclub.com/forum/the-average- ... 14554.html https://gmatclub.com/forum/set-x-consis ... 05656.html https://gmatclub.com/forum/three-pieces ... 35503.html

BNDN · Answer

This is a great question that’s helpful for learning.

MrinmoyNegel · Answer

I like the solution - it’s helpful. Good question and explanation

crimson_noise · Answer

I like the solution - it’s helpful. Simple, effective and useful!

ghost0 · Answer

I did not quite understand the solution. The qs is asking about the new range. Shouldn't the number of students now be 21 instead of 20 here and then we proceed with the calculation

Bunuel · Answer

The number of students is 21, yes, but the solution is correctly using only the original 20 students to calculate the  initial distribution  (min and max) before adding the new student. Then it adds the new student (who weighs 61 kg) to compute the  new  range. So the logic is correct. Please review the solution and the discission once more.

Bikram35279 · Answer

I like the solution - it’s helpful.

1UPantyhose · Answer

I like the solution - it’s helpful.

dishantkamboj123 · Answer

I don’t quite agree with the solution. Wasn't the solution required for the new class with 41 strentgh.

Bunuel · Answer

This is a hard question and it’s okay if you don’t get it the first time. That’s why it’s important to review the solution carefully.

The range being asked about is for the  new class of 21 students  (after the extra student joined). The old 20-student setup is only used to figure out the possible distribution of weights, which then determines how the new student’s 61 kg weight changes the extremes. So yes, the official solution is already solving for the 21-student class, not just the original 20.

mogamogh · Answer

I like the solution - it’s helpful.

mkeshri185 · Answer

Why we are not doing naything with the highest weight person? Why are we only concerned with max and min the lowest weight student ? The range can be affected by both low and high

Bunuel · Answer

The highest weight is already tied to the lowest weight because the difference between them is fixed at 10. So once you decide the lowest possible weight, the highest is automatically determined as lowest + 10. That is why the solution only varies the minimum weight, adjusting that also adjusts the maximum weight at the same time, and the range follows directly.

Diegoram17 · Answer

I like the solution - it’s helpful.

hbhura · Answer

I like the solution - it’s helpful.

cumvelit · Answer

I like the solution - it’s helpful.

quialias · Answer

I did not quite understand the solution. I did not get how the remaining students were taken as x+10, can someone explain this in detail.

Bunuel · Answer

Try alternative solutions here: https://gmatclub.com/forum/in-a-class-o ... 23266.html Hope it helps.

ishaan452356 · Answer

I like the solution - it’s helpful.

I12-07

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